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Document and Entity Information Document - USD ($)	12 Months Ended
Document and Entity Information Document - USD ($)	Dec. 31, 2019	Jan. 29, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	0-27756
Entity Registrant Name	ALEXION PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	13-3648318
Entity Address, Address Line One	121 Seaport Boulevard
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02210
City Area Code	475
Local Phone Number	230-2596
Title of 12(b) Security	Common Stock $0.0001 par value
Trading Symbol	ALXN
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 28,243,087,610
Entity Common Stock, Shares Outstanding		221,400,872
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement to be used in connection with its 2020 Annual Meeting of Stockholders currently anticipated to be held on May 13, 2020, are incorporated by reference into Part III of this report.
Entity Central Index Key	0000899866
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false

Consolidated Balance Sheets Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets [Abstract]
Cash and cash equivalents	$ 2,685.5	$ 1,365.5
Marketable securities	64.0	198.3
Trade accounts receivable, net	1,243.2	922.3
Inventories	627.6	472.5
Prepaid expenses and other current assets	456.1	426.4
Total current assets	5,076.4	3,385.0
Property, plant and equipment, net	1,163.3	1,471.5
Intangible assets, net	3,344.3	3,641.3
Goodwill	5,037.4	5,037.4
Right of use operating assets	204.0	0.0
Deferred tax assets	2,290.2	101.8
Other assets	429.0	294.9
Total assets	17,544.6	13,931.9
Liabilities and Equity [Abstract]
Accounts payable and accrued expenses	966.7	698.2
Revolving credit facility	0.0	250.0
Current portion of long-term debt	126.7	93.8
Current portion of contingent consideration	0.0	97.6
Other current liabilities	100.9	34.4
Total current liabilities	1,194.3	1,174.0
Long-term debt, less current portion	2,375.0	2,501.7
Contingent consideration	192.4	183.2
Facility lease obligations	0.0	361.0
Deferred tax liabilities	2,081.4	391.1
Noncurrent operating lease liabilities	164.1	0.0
Other liabilities	265.6	155.6
Total liabilities	6,272.8	4,766.6
Stockholders' Equity Attributable to Parent [Abstract]
Commitments and contingencies (Note 11)
Common stock, $.0001 par value; 290.0 shares authorized; 237.8 and 236.2 shares issued at 2019 and 2018, respectively	0.0	0.0
Additional paid-in capital	8,804.7	8,539.1
Treasury stock, at cost, 16.5 and 12.7 shares at 2019 and 2018, respectively	(2,105.9)	(1,689.9)
Accumulated other comprehensive loss	(66.8)	(9.7)
Retained earnings	4,639.8	2,325.8
Total stockholders' equity	11,271.8	9,165.3
Total liabilities and stockholders' equity	$ 17,544.6	$ 13,931.9

Consolidated Balance Sheets (Parenthetical) - $ / shares shares in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	290.0	290.0
Common stock, shares issued	237.8	236.2
Treasury Stock, Shares	16.5	12.7

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total revenues	$ 4,991.1	$ 4,131.2	$ 3,551.1
Cost of sales:
Cost of sales	394.5	374.3	454.2
Operating expenses:
Research and development	886.0	730.4	878.4
Selling, general and administrative	1,261.1	1,111.8	1,094.4
Acquired in-process research and development	(4.1)	1,183.0	0.0
Amortization of purchased intangible assets	309.6	320.1	320.1
Change in fair value of contingent consideration	11.6	116.5	41.0
Restructuring expenses	12.0	25.5	104.6
Impairment of intangible assets	0.0	0.0	31.0
Total operating expenses	2,476.2	3,487.3	2,469.5
Operating income	2,120.4	269.6	627.4
Other income and expense:
Investment income	100.3	65.3	18.5
Interest expense	(77.8)	(98.2)	(98.4)
Other income and (expense)	35.9	5.5	0.3
Income before income taxes	2,178.8	242.2	547.8
Income tax (benefit) expense	(225.5)	164.6	104.5
Net income	$ 2,404.3	$ 77.6	$ 443.3
Earnings per common share
Basic (in dollars per share)	$ 10.77	$ 0.35	$ 1.98
Diluted (in dollars per share)	$ 10.70	$ 0.35	$ 1.97
Shares used in computing earnings per common share
Basic (in shares)	223.2	222.7	223.9
Diluted (in shares)	224.8	224.5	225.4
Net product sales
Total revenues	$ 4,990.0	$ 4,130.1	$ 3,549.5
Other revenue
Total revenues	$ 1.1	$ 1.1	$ 1.6

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 2,404.3	$ 77.6	$ 443.3
Foreign currency translation	(1.0)	(0.5)	8.4
Unrealized gains (losses) on debt securities	0.2	(0.5)	0.6
Unrealized gains (losses) on pension obligation	(6.6)	2.2	1.9
Unrealized gains (losses) on hedging activities, net of tax of $(14.5), $7.3 and $(59.0), respectively	(49.7)	23.5	(105.8)
Other comprehensive income (loss), net of tax	(57.1)	24.7	(94.9)
Comprehensive income	$ 2,347.2	$ 102.3	$ 348.4

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Consolidated Statement of Comprehensive Income (Parentheticals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Unrealized gains (losses) on hedging activities - tax effect	$ (14.5)	$ 7.3	$ (59.0)

Statement of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock at Cost [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings
Balances, common shares at Dec. 31, 2016		231.9
Balances, treasury shares at Dec. 31, 2016				8.0
Balances, value at Dec. 31, 2016	$ 8,693.8	$ 0.0	$ 7,957.0	$ (1,141.3)	$ 60.5	$ 1,817.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock, shares				4.0
Repurchase of common stock value	(463.6)			$ (463.6)
Issuance of common stock from exercise of options, shares		1.3
Issuance of common stock from exercise of options, value	85.9		85.9
Issuance of restricted common stock, shares		1.1
Share-based compensation expense, value	247.4		247.4
Net income (loss)	443.3					443.3
Other comprehensive income (loss)	(94.9)				(94.9)
Balances, common shares at Dec. 31, 2017		234.3
Balances, treasury shares at Dec. 31, 2017				12.0
Balances, value at Dec. 31, 2017	8,893.1	$ 0.0	8,290.3	$ (1,604.9)	(34.4)	2,242.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new guidance, value	(18.8)					(18.8)
Repurchase of common stock, shares		0.0		0.7
Repurchase of common stock value	(85.0)			$ (85.0)
Issuance of common stock from exercise of options, shares		0.6
Issuance of common stock from exercise of options, value	47.6		47.6
Issuance of restricted common stock, shares		1.3
Issuance of restricted common stock	(0.3)		(0.3)
Share-based compensation expense, value	201.5		201.5
Net income (loss)	77.6					77.6
Other comprehensive income (loss)	$ 24.7				24.7
Balances, common shares at Dec. 31, 2018		236.2
Balances, treasury shares at Dec. 31, 2018	12.7			12.7
Balances, value at Dec. 31, 2018	$ 9,165.3	$ 0.0	8,539.1	$ (1,689.9)	(9.7)	2,325.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new guidance, value	6.1					6.1
Repurchase of common stock, shares				3.8
Repurchase of common stock value	$ (416.0)			$ (416.0)
Issuance of common stock from exercise of options, shares	0.3	0.4
Issuance of common stock from exercise of options, value	$ 29.9		29.9
Issuance of restricted common stock, shares		1.2
Issuance of restricted common stock	0.0		0.0
Share-based compensation expense, value	235.7		235.7
Net income (loss)	2,404.3					2,404.3
Other comprehensive income (loss)	$ (57.1)				(57.1)
Balances, common shares at Dec. 31, 2019		237.8
Balances, treasury shares at Dec. 31, 2019	16.5			16.5
Balances, value at Dec. 31, 2019	$ 11,271.8	$ 0.0	$ 8,804.7	$ (2,105.9)	$ (66.8)	4,639.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new guidance, value	$ (90.3)					$ (90.3)

Statement of Cash Flows $ in Millions	12 Months Ended
Statement of Cash Flows $ in Millions	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Cash flows from operating activities:
Net income (loss)	$ 2,404.3	$ 77.6	$ 443.3
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	376.8	405.3	496.7
Impairment of assets	0.0	13.5	118.8
Change in fair value of contingent consideration	11.6	116.5	41.0
Payments of contingent consideration	(100.0)	0.0	(18.0)
Share-based compensation expense	237.0	203.0	243.1
Non-cash expense for acquired IPR&D	0.0	64.6	0.0
Deferred tax (benefit) expense	(455.4)	32.9	(45.9)
Unrealized foreign currency (gain) loss	(2.1)	4.8	(9.4)
Unrealized (gain) loss on forward contracts	(16.5)	(15.8)	11.1
Unrealized gain on strategic equity investments	(26.9)	(40.2)	0.0
Gain on sale of strategic equity investments	(32.8)	0.0	0.0
Gain on modification of purchase option	(32.0)	0.0	0.0
Other	(2.7)	(2.0)	5.4
Changes in operating assets and liabilities, excluding the effect of acquisitions:
Accounts receivable	(319.2)	(208.8)	(55.2)
Inventories	(156.9)	(14.7)	(88.2)
Prepaid expenses, right of use operating assets and other assets	(31.0)	(155.6)	(137.2)
Accounts payable, accrued expenses, lease liabilities and other liabilities	230.7	(55.1)	110.1
Net cash provided by operating activities	2,084.9	426.0	1,115.6
Cash flows from investing activities:
Purchases of available-for-sale debt securities	(80.2)	(782.7)	(1,648.8)
Proceeds from maturity or sale of available-for-sale debt securities	222.2	1,473.5	1,089.9
Purchases of mutual funds related to nonqualified deferred compensation plan	(17.6)	(12.1)	(9.9)
Proceeds from sale of mutual funds related to nonqualified deferred compensation plan	14.7	12.3	7.7
Purchases of property, plant and equipment	(154.7)	(213.0)	(357.3)
Purchases of strategic equity investments	(73.3)	(10.3)	0.0
Proceeds from sale of strategic equity investments	114.7	0.0	0.0
Purchases of intangible assets	(16.0)	0.0	0.0
Other	(0.1)	2.8	0.1
Net cash provided by (used in) investing activities	9.7	470.5	(918.3)
Cash flows from financing activities:
Proceeds from revolving credit facility	0.0	250.0	0.0
Payments on revolving credit facility	(250.0)
Payments on term loan	(98.0)	(293.8)	(175.0)
Repurchase of common stock	(416.0)	(85.0)	(463.6)
Net proceeds from issuance of stock under share-based compensation arrangements	29.9	47.3	85.9
Payments of contingent consideration	0.0	0.0	(7.0)
Repayment of development-related grants	0.0	0.0	(26.0)
Other	(5.0)	(20.9)	(10.9)
Net cash used in financing activities	(739.1)	(102.4)	(596.6)
Effect of exchange rate changes on cash and cash equivalents and restricted cash	0.8	(11.2)	17.7
Net change in cash and cash equivalents and restricted cash	1,356.3	782.9	(381.6)
Cash and cash equivalents and restricted cash at beginning of period	1,367.3	584.4	966.0
Cash and cash equivalents and restricted cash at end of period	2,723.6	1,367.3	584.4
Supplemental disclosures
Cash paid for interest (net of amounts capitalized)	72.6	90.9	95.3
Cash paid for income taxes	187.9	163.9	162.1
Other Significant Noncash Transaction, Value of Consideration Given	75.0	0.0	0.0
Supplemental cash flow disclosures from investing and financing activities:
Operating ROU lease assets obtained in exchange for operating lease liabilities	27.5	0.0	0.0
Capitalization of construction costs related to facility lease obligations	0.0	44.8	121.8
Accounts payable and accrued expenses for purchases of property, plant and equipment and intangible assets	13.3	21.4	34.7
Cash and cash equivalents	2,685.5	1,365.5	584.4
Restricted cash included in other current assets	37.8	0.1	0.0
Restricted cash included in other noncurrent assets	$ 0.3	$ 1.7	$ 0.0

Business Overview and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Business Overview and Summary of Significant Accounting Policies [Abstract]

Business Overview and Summary of Significant Accounting Policies

Business

Alexion Pharmaceuticals, Inc. (Alexion, the Company, we, our or us) is a global biopharmaceutical company focused on serving patients and families affected by rare diseases through the discovery, development and commercialization of life-changing therapies.

As the global leader in complement biology and inhibition for more than 20 years, Alexion has developed and commercializes two approved complement inhibitors to treat patients with paroxysmal nocturnal hemoglobinuria (PNH) and atypical hemolytic uremic syndrome (aHUS), as well as the first and only approved complement inhibitor to treat anti-acetylcholine receptor (AChR) antibody-positive generalized myasthenia gravis (gMG) and neuromyelitis optica spectrum disorder (NMOSD) in patients who are anti-aquaporin-4 (AQP4) antibody positive. Alexion also has two highly innovative enzyme replacement therapies and the first and only approved therapies for patients with life-threatening and ultra-rare metabolic disorders, hypophosphatasia (HPP) and lysosomal acid lipase deficiency (LAL-D).

In addition to our marketed therapies, we have a diverse pipeline resulting from internal innovation and business development. Alexion focuses its research efforts on novel molecules and targets in the complement cascade and its development efforts on the core therapeutic areas of hematology, nephrology, neurology, metabolic disorders and cardiology. We were incorporated in 1992 under the laws of the State of Delaware.

Basis of Presentation and Principles of Consolidation

The accompanying consolidated financial statements include the accounts of Alexion and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. For each of our business combinations, all of the assets acquired and liabilities assumed were recorded at their respective fair values as of the date of acquisition, and their results of operations are included in the consolidated financial statements from the date of acquisition.

Dividend Policy

We have never paid a cash dividend on shares of our stock. We currently intend to retain our earnings to finance future operations and do not anticipate paying any cash dividends on our stock in the foreseeable future.

Critical Accounting Estimates

The preparation of our consolidated financial statements, which have been prepared in accordance with accounting principles generally accepted in the U.S., requires us to make estimates, judgments and assumptions that may affect the reported amounts of assets, liabilities, revenues, expenses and related disclosure of contingent assets and liabilities in our financial statements. We believe the most complex judgments result primarily from the need to make estimates about the effects of matters that are inherently uncertain and are significant to our consolidated financial statements. We base our estimates on historical experience and on various other assumptions that we believe are reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. We evaluate our estimates, judgments and assumptions on an ongoing basis. Actual results may differ from these estimates under different assumptions or conditions and such differences may be material.

The most significant areas involving estimates, judgments and assumptions used in the preparation of our consolidated financial statements are as follows:


•	Revenue recognition;


•	Contingent liabilities;


•	Share-based compensation;


•	Valuation of goodwill, acquired intangible assets and in-process research and development (IPR&D);


•	Valuation of contingent consideration; and


•	Income taxes.

Foreign Currency Translation

The financial statements of our subsidiaries with functional currencies other than the U.S. dollar are translated into U.S. dollars using period-end exchange rates for assets and liabilities, historical exchange rates for stockholders’ equity and weighted average exchange rates for operating results. Translation gains and losses are included in accumulated other comprehensive income (loss), net of tax, in stockholders’ equity. Foreign currency transaction gains and losses are included in the results of operations in other income and expense.

Cash and Cash Equivalents

Cash and cash equivalents are stated at cost plus accrued interest, which approximates fair value, and include short-term highly liquid investments with original maturities of three months or less. As of December 31, 2019 and 2018, cash equivalents were comprised of money market funds and other debt securities with maturities less than 90 days from the date of purchase.

Fair Value of Financial Instruments

The carrying amounts reflected in the consolidated balance sheets for cash and cash equivalents, accounts receivable, other assets, accounts payable, accrued expenses and other liabilities approximate fair value due to their short-term maturities. Our marketable securities are valued based upon pricing of securities with similar investment characteristics and holdings. Our mutual fund investments and equity securities are valued based on quoted market prices in active markets with no valuation adjustment. Investments in equity securities of publicly traded companies which are subject to holding period restrictions are carried at fair value using an option pricing valuation model and observable market inputs such as the historical volatility of similar companies and risk-free interest rates. Our derivative financial instruments are measured at fair value using observable market inputs such as forward rates, interest rates, our own credit risk and our counterparties’ credit risks. Our debt obligations are carried at historical cost, which approximates fair value. Our contingent consideration liabilities related to our acquisitions and derivative liabilities associated with certain option agreements are valued based on various estimates, including probability of success, estimated revenues, discount rates and amount of time until the conditions of the milestone payments are met.

Marketable Securities

We invest our excess cash balances in marketable securities of highly rated financial institutions and investment-grade debt instruments. We seek to diversify our investments and limit the amount of investment concentrations for individual institutions, maturities and investment types. We classify marketable debt securities as available-for-sale and, accordingly, record such securities at fair value. We classify these securities as current assets as these investments are intended to be available to the Company for use in funding current operations.

Unrealized gains and losses on our marketable debt securities that are deemed temporary are included in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity. If any adjustment to fair value reflects a significant decline in the value of the security, we evaluate the extent to which the decline is determined to be other-than-temporary and would mark the security to market through a charge to our consolidated statement of operations. Credit losses are identified when we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security. In the event of a credit loss, only the amount associated with the credit loss is recognized in operating results, with the amount of loss relating to other factors recorded in accumulated other comprehensive income (loss).

We sponsor a nonqualified deferred compensation plan which allows certain highly-compensated employees to elect to defer income to future periods. Participants in the plan earn a return on their deferrals based on several investments options, which mirror returns on underlying mutual fund investments. We choose to invest in the underlying mutual fund investments to offset the liability associated with our nonqualified deferred compensation plan. These mutual fund investments are valued at net asset value per share and are carried at fair value with gains and losses included in investment income. The changes in the underlying liability to the employee are recorded in operating expenses.

Accounts Receivable

Our standard credit terms vary based on the country of sale and range from 30 to 120 days and all arrangements are payable within one year of the transfer of the product. Our consolidated average days’ sales outstanding ranges from 70 to 80 days. We evaluate the creditworthiness of customers on a regular basis. The length of time from sale to receipt of payment in certain countries exceeds our credit terms. In countries in which collections from customers extend beyond normal payment terms, we seek to collect interest. We record interest on customer receivables as interest income when collected. Subsequent adjustments for further declines in credit rating are recorded as bad debt expense as a component of selling, general and administrative expense. We also use judgments as to our ability to collect outstanding receivables and provide allowances for the portion of receivables if and when collection becomes doubtful, and we also assess on an ongoing basis whether collectibility is probable at the time of sale. As of December 31, 2019 and 2018, allowances on receivables were not material.

Concentration of Credit Risk

Financial instruments that potentially expose the Company to concentrations of credit risk are limited to cash equivalents, marketable securities, accounts receivable and our foreign exchange derivative contracts. We invest our cash reserves in money market funds or high-quality marketable debt securities in accordance with our investment policy. The stated objectives of our investment policy are to preserve capital, provide liquidity consistent with forecasted cash flow requirements, maintain appropriate diversification and generate returns relative to these investment objectives and prevailing market conditions.

At December 31, 2019, four customers accounted for 66.9% of the accounts receivable balance, with these individual customers ranging from 11.6% to 20.3% of the accounts receivable balance. At December 31, 2018, three customers accounted for 48.7% of the accounts receivable balance, with these individual customers ranging from 14.0% to 19.1% of the accounts receivable balance.

For the year ended December 31, 2019, four customers accounted for 56.4% of our product sales, with these individual customers ranging from 10.0% to 16.8% of our product sales. For the year ended December 31, 2018, four customers accounted for 50.3% of our product sales, with these individual customers ranging from 10.0% to 16.4% of our product sales. For the year ended December 31, 2017, three customers accounted for 37.0% of our product sales, with these individual customers ranging from 10.8% to 15.0% of our product sales. No other customers accounted for more than 10.0% of accounts receivable or net product sales.

We continue to monitor economic conditions, including volatility associated with international economies and the associated impacts on the financial markets and our business. Substantially all of our accounts receivable are due from wholesale distributors, public hospitals and other government entities. We monitor the financial performance of our customers so that we can appropriately respond to changes in their credit worthiness. We operate in certain jurisdictions where weakness in economic conditions can result in extended collection periods. To date, we have not experienced any significant losses with respect to collection of our accounts receivable.

Inventories

Inventories are stated at the lower of cost or net realizable value. Cost is determined in a manner that approximates average costs.

The components of inventory are as follows:



	December 31,
	2019		2018
Raw materials	$	41.2	$	31.4
Work-in-process	180.8		90.4
Finished goods	405.6		350.7
	$	627.6	$	472.5

Capitalization of Inventory Costs

We capitalize inventory produced for commercial sale, which may include costs incurred for certain products awaiting regulatory approval, or for inventory produced at new production facilities, when management considers it probable that the pre-approval inventories will be saleable. We capitalize inventory produced in preparation of product launches sufficient to support estimated initial market demand. Capitalization of such inventory begins when we have (i) obtained positive results in clinical trials that we believe are necessary to support regulatory approval, (ii) concluded that uncertainties regarding regulatory approval of the product and facilities have been sufficiently reduced, and (iii) determined that the inventory has probable future economic benefit. In evaluating whether these conditions have been met, we consider clinical trial results for the underlying product candidate, results from meetings with regulatory authorities, the compilation of the regulatory application, and how far a facility has progressed along the approval process. If we are aware of any material risks or contingencies outside of the standard regulatory review and approval process, or if there are any specific negative issues identified relating to the safety, efficacy, manufacturing, marketing or labeling of the product that would have a significant negative impact on its future economic benefits, the related inventory would not be capitalized. As of December 31, 2019, the carrying value of inventory at unapproved production facilities was $60.5.

Products that have been approved by the U.S. Food and Drug Administration (FDA) or other regulatory authorities are also used in clinical programs to assess the safety and efficacy of the products for usage in diseases that have not been approved by the FDA or other regulatory authorities. The form of the products utilized for both commercial and clinical programs is identical and, as a result, the inventory has an “alternative future use” as defined in authoritative guidance. Raw materials and purchased drug product associated with clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes and, therefore, does not have an “alternative future use”.

For products which are under development and have not yet been approved by regulatory authorities, purchased drug product is charged to research and development expense upon delivery. Delivery occurs when the inventory passes quality inspection and ownership transfers to us. Nonrefundable advance payments for research and development activities, including production of purchased drug product, are deferred and capitalized until the goods are delivered. We also recognize expense for raw materials purchased for developmental purposes when the raw materials pass quality inspection and we have an obligation to pay for the materials.

Inventory Write-Offs

We analyze our inventory levels to identify inventory that may expire prior to sale, inventory that has a cost basis in excess of its estimated realizable value, or inventory in excess of expected sales requirements. Although the manufacturing of our product is subject to strict quality control, certain batches or units of product may no longer meet quality specifications or may expire, which requires adjustments to our inventory values. We also apply judgment related to the results of quality tests that we perform throughout the production process, as well as our understanding of regulatory guidelines, to determine if it is probable that inventory will be saleable. These quality tests are performed throughout the pre-and post-production process, and we continually gather additional information regarding product quality for periods after the manufacture date. Our products currently have a maximum estimated life ranging from 36 to 48 months and, based on our sales forecasts, we expect to realize the carrying value of our inventory. In the future, reduced demand, quality issues or excess supply beyond those anticipated by management may result in a material adjustment to inventory levels, which would be recorded as an increase to cost of sales.

The determination of whether or not inventory costs will be realizable requires estimates by our management. A critical input in this determination is future expected inventory requirements based on internal sales forecasts. We then compare these requirements to the expiry dates of inventory on hand. For inventories that are capitalized in preparation of product launch, we also consider the expected approval date in assessing realizability. To the extent that inventory is expected to expire prior to being sold, we will write down the value of inventory.

Derivative Instruments

We record the fair value of derivative instruments as either assets or liabilities on the balance sheet. The accounting for gains and losses resulting from changes in fair value is dependent on the use of the derivative and whether it is designated and qualifies for hedge accounting.

All qualifying hedging activities are documented at the inception of the hedge and must meet the definition of highly effective in offsetting changes to future cash. On a quarterly basis, we perform an assessment to confirm that

outstanding hedges remain highly effective and continue to qualify for hedge accounting. We record the fair value of the qualifying hedges in prepaid expenses and other current assets, other assets, other current liabilities and other liabilities. All unrealized gains and losses on derivatives that are designated and qualify for hedge accounting are reported in other comprehensive income (loss) and recognized when the underlying hedged transaction affects earnings. When the forecasted transaction occurs, this amount is reclassified into the consolidated statement of operations and presented in the same financial statement line item as the hedged item.

Derivative instruments for which hedge accounting is not applied are recorded at fair value in prepaid expenses and other current assets and other current liabilities. Unrealized gains and losses resulting from changes in the fair value of these derivatives are reported in other income and expense.

Property, Plant and Equipment

Property, plant and equipment are stated at cost and are depreciated on a straight-line basis over the estimated useful lives of the assets. We estimate economic lives as follows:


•	Building and improvements—fifteen to thirty five years


•	Machinery and laboratory equipment—five to fifteen years


•	Computer hardware and software—three to seven years


•	Furniture and office equipment— five to ten years

Leasehold improvements and assets under financing lease arrangements are amortized over the lesser of the asset’s estimated useful life or the term of the respective lease. Maintenance costs are expensed as incurred.

Construction-in-progress reflects amounts incurred for property, plant, or equipment construction or improvements that have not been placed in service.

Leases

At the inception of an arrangement, we determine if an arrangement is, or contains, a lease based on the unique facts and circumstances present in that arrangement. Lease classification, recognition, and measurement are then determined at the lease commencement date. For arrangements that contain a lease we (i) identify lease and non-lease components, (ii) determine the consideration in the contract, (iii) determine whether the lease is an operating or financing lease; and (iv) recognize lease ROU assets and liabilities. Lease liabilities and their corresponding ROU assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable and as such, we use our incremental borrowing rate based on the information available at the lease commencement date, which represents an internally developed rate that would be incurred to borrow, on a collateralized basis, over a similar term, an amount equal to the lease payments in a similar economic environment.

Most leases include options to renew and, or, terminate the lease, which can impact the lease term. The exercise of these options is at our discretion and we do not include any of these options within the expected lease term as we are not reasonably certain we will exercise these options. We have elected to combine lease components (for example fixed payments including rent) with non-lease components (for example, non-dedicated parking and common-area maintenance costs) on our real estate and commercial fleet asset classes. We separate lease and non-lease components on our embedded contract manufacturing organization (CMO) arrangements. Lease and non-lease components on these CMO arrangements are determined based on an allocation of the consideration in the contract to the embedded lease and non-lease components of the arrangement based on the relative standalone prices of these components.

Fixed, or in substance fixed, lease payments on operating leases are recognized over the expected term of the lease on a straight-line basis, while fixed, or in substance fixed, payments on financing leases are recognized using the effective interest method. Variable lease expenses that are not considered fixed, or in substance fixed, are recognized as incurred. Fixed and variable lease expense on operating leases is recognized within operating expenses within our consolidated statements of operations. Financing lease ROU asset amortization and interest costs are recorded within operating expenses and interest expense, respectively, within our consolidated statements of operations. We have operating and financing leases for corporate offices, research and development facilities, regional executive and sales offices, commercial fleet, and CMO embedded lease arrangements. We have elected the short-term lease exemption and, therefore, do not recognize a ROU asset or corresponding liability for lease arrangements with an original term of 12 months or less.

Operating leases are included in right of use operating assets, other current liabilities, and noncurrent operating lease liabilities in our consolidated balance sheet as of December 31, 2019. Financing leases are included in property, plant and equipment, other current liabilities, and other liabilities in our consolidated balance sheet as of December 31, 2019.

Assets Held for Sale

We classify assets as held for sale when the following criteria are met: i) management, having the authority to approve the action, commits to a plan to sell the asset, ii) the asset is available for immediate sale in its present condition subject only to terms that are usual and customary for sales of similar assets, iii) an active program to locate a buyer and other actions required to complete the plan to sell the asset have been initiated, iv) the sale of the asset is probable, and transfer of the asset is expected to qualify for recognition as a completed sale, within one year, v) the asset is being actively marketed for sale at a price that is reasonable in relation to its current fair value, and vi) actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. Assets that are classified as held for sale are recorded at the lower of their carrying value or their fair value less the costs to sell.

In the third quarter 2017, we announced our intention to close the Alexion Rhode Island Manufacturing Facility (ARIMF). In the fourth quarter 2017, we met the criteria for assets held for sale and reclassified the ARIMF assets from property, plant and equipment to assets held for sale recorded within prepaid expenses and other current assets. We subsequently sold ARIMF during the third quarter of 2018. See Note 18, Restructuring and Related Expenses.

Manufacturing Facilities

We capitalize costs incurred for the construction of facilities which support commercial manufacturing. We also capitalize costs related to validation activities which are directly attributable to preparing the facility for its intended use, including engineering runs and inventory production necessary to obtain approval of the facility from government regulators for the production of a commercially approved drug. When the facility is substantially complete and ready for its intended use and regulatory approval for commercial production has been received, we will place the asset in service.

The production of inventory for preparing the facility for its intended use requires two types of production: engineering runs which are used for testing purposes only and do not result in saleable inventory, and validation runs which are used for validating equipment and may result in saleable inventory. The costs associated with inventory produced during engineering runs and normal production losses during validation runs are capitalized to fixed assets and depreciated over the asset’s useful life. Saleable inventory produced during the validation process is initially treated as a fixed asset; however, upon regulatory approval, this inventory is reclassified to inventory and expensed in cost of goods sold as product is sold, or in research and development expenses as product is utilized in R&D activities. Abnormal production costs incurred during the validation process are expensed as incurred.

Acquisitions

Business combinations are accounted for using the acquisition method of accounting. Under the acquisition method of accounting, the tangible and intangible assets acquired and the liabilities assumed are recorded as of the acquisition date at their respective fair values. We evaluate a business as an integrated set of activities and assets that is capable of being conducted and managed for the purpose of providing a return in the form of dividends, lower costs or other economic benefits and consists of inputs and substantive processes applied to those inputs that have the ability to contribute to the creation of outputs. If substantially all of the fair value of gross assets acquired is concentrated in a single asset or group of similar identifiable assets, the assets do not represent a business. In an acquisition of a business, the excess of the fair value of the consideration transferred over the fair value of the net assets acquired is recorded as goodwill.

Acquisitions of assets or a group of assets that do not meet the definition of a business are accounted for as asset acquisitions using the cost accumulation method, whereby the cost of the acquisition, including certain transaction costs, is allocated to the assets acquired on the basis of relative fair values. No goodwill is recognized in an asset acquisition. Intangible assets that are acquired in an asset acquisition for use in research and development activities which have an alternative future use are capitalized as in-process research and development (IPR&D). Acquired IPR&D which has no alternative future use is recognized as research and development expense at acquisition. Contingent milestone payments associated with asset acquisitions are recognized when probable and estimable. These amounts are expensed to research and development if there is no alternative future use associated with the asset, or capitalized as an intangible asset if alternative future use of the asset exists.

Our consolidated financial statements include the results of operations of an acquired business after the completion of the acquisition.

Contingent Consideration

We record contingent consideration resulting from a business combination at fair value on the acquisition date. On a quarterly basis, we revalue these obligations and record increases or decreases in their fair value as an adjustment to operating earnings. Changes to contingent consideration obligations can result from adjustments to discount rates, accretion of the liability due to the passage of time, changes in our estimates of the likelihood or timing of achieving development or commercial milestones, changes in the probability of certain clinical events or changes in the assumed probability associated with regulatory approval.

Intangible Assets

Our intangible assets generally consist of licensing rights, patents, purchased technology, acquired IPR&D and other intangibles. Intangible assets with definite lives are amortized based on their pattern of economic benefit over their estimated useful lives and reviewed periodically for impairment.

Intangible assets related to IPR&D projects are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. During the period the assets are considered indefinite-lived, they will not be amortized but will be tested for impairment. Impairment testing is performed at least annually or when a triggering event occurs that could indicate a potential impairment. If and when development is complete, which generally occurs when regulatory approval to market a product is obtained, the associated assets are deemed finite-lived and are amortized over a period that best reflects the economic benefits provided by these assets.

Goodwill

Goodwill represents the excess of purchase price over fair value of net assets acquired in a business combination and is not amortized. Goodwill is subject to impairment testing at least annually or when a triggering event occurs that could indicate a potential impairment. We are organized and operate as a single reporting unit and therefore the goodwill impairment test is performed using our overall market value, as determined by our traded share price, compared to our book value of net assets.

Impairment of Long-Lived Assets

Our long-lived assets are primarily comprised of intangible assets and property, plant and equipment. We evaluate our finite-lived intangible assets and property, plant and equipment, for impairment whenever events or changes in circumstances indicate the carrying value of an asset or group of assets is not recoverable. If these circumstances exist, recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset group to future undiscounted net cash flows expected to be generated by the asset group. If such assets are considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the assets exceeds the fair value of the assets.

In addition, indefinite-lived intangible assets, comprised of IPR&D, are reviewed for impairment annually and whenever events or changes in circumstances indicate that it is more likely than not that the asset is impaired by comparing the fair value to the carrying value of the asset. In the second quarter 2017, we recognized an impairment charge of $31.0 related to our SBC-103 acquired in-process research and development asset due to clinical results.

Other Investments

From time to time, we make strategic investments in equity securities of certain biotechnology companies which we acquire in connection with license and option agreements. Our strategic investment portfolio may include equity securities in publicly traded companies, as well as investments in companies with securities that are not publicly traded and where fair value is not readily available. These investments are included in other assets in our consolidated balance sheets.

We have historically recorded our investments in securities that are not publicly traded at cost, less impairments. Beginning January 1, 2018, we continue to record these investments at cost, less impairments; however, we also adjust the investment for any changes resulting from an observable price change in an orderly transaction for identical or similar investments of the same issuer. We assess relevant transactions that occur on or before the balance sheet date to identify observable price changes, and we regularly monitor these investments to evaluate whether there is an indication that the investment is impaired, based on the implied value of recent company financings, public market prices of comparable companies, and general market conditions.

Our investments in equity securities in publicly traded companies which are unrestricted are regularly measured and carried at fair value and classified as Level 1 equity securities within the fair value hierarchy. Investments in publicly traded companies which are subject to holding period restrictions are carried at fair value using an option pricing valuation model and classified as Level 2 equity securities within the fair value hierarchy. The most significant assumptions within the option pricing valuation model are the term of the restrictions and the stock price volatility, which is based upon the historical volatility of the applicable company or similar companies. We also use a constant maturity risk-free interest rate to match the remaining term of the restrictions on such investments.

Contingent Liabilities

We are currently involved in various claims and legal proceedings. On a quarterly basis, we review the status of each significant matter and assess its potential financial exposure. If the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated, we accrue a liability for the estimated loss. Because of uncertainties related to claims and litigation, accruals are based on the best information available at the time of our assessment including the legal facts and circumstances of the case, status of the proceedings, applicable law and the likelihood of settlement, if any. On a periodic basis, as additional information becomes available, or based on specific events such as the outcome of litigation or settlement of claims (and our offers of settlement), we may reassess the potential liability related to these matters and may revise these estimates when facts and circumstances indicate the need for changes.

Treasury Stock

Treasury stock is accounted for using the cost method, with the purchase price of the common stock recorded separately as a deduction from stockholders’ equity.

Revenue Recognition

In May 2014, the FASB issued a comprehensive new standard which amends revenue recognition principles. We adopted the new standard on January 1, 2018 by applying the modified retrospective method to all contracts that were not completed as of that date. Under the new guidance, revenue is recognized when a customer obtains control of promised goods or services, in an amount that reflects the consideration expected to be received in exchange for those goods or services. Revenue is recognized through a five-step process: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) a performance obligation is satisfied. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, the Company assesses the goods or services promised within each contract, and determines those that are performance obligations. Revenue is recognized for the applicable performance element when each distinct performance obligation is satisfied.

While results for reporting periods beginning after January 1, 2018 are presented under the new guidance, prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for the prior period. Upon adoption of the new revenue recognition standard, on January 1, 2018, we reduced our deferred revenue balance by $10.4, with an offsetting increase of $6.0 in retained earnings due to the cumulative impact of adopting

this new standard. The impact to net product sales and net income for the year ended December 31, 2018 was an increase of $5.3 and $4.8, respectively. The new standard also resulted in a decrease of $17.9 in deferred revenue and an increase of $10.8 in retained earnings as of December 31, 2018. The adoption of the new revenue standard did not have a material impact on any other balances within the consolidated financial statements as of and for the year ended December 31, 2018. The adoption of the new standard did not significantly change our accounting policies.

Nature of Products

Our principal source of revenue is product sales. Our contracts with customers generally contain a single performance obligation and we recognize revenue from product sales when we have satisfied our performance obligation by transferring control of the product to our customers. Control of the product generally transfers to the customer upon delivery. In certain countries, we sell to distributors on a consignment basis and record revenue when control of the product transfers to the customer upon sale to the end user.

Our customers are primarily comprised of distributors, pharmacies, hospitals, hospital buying groups, and other healthcare providers. In some cases, we may also sell to governments and government agencies. In addition to sales in countries where our products are commercially available, we have also recorded revenue on sales for patients receiving treatment through named-patient programs. The relevant authorities or institutions in those countries have agreed to reimburse for product sold on a named-patient basis where our products have not received final approval for commercial sale.

Revenue is recognized at the amount to which we expect to be entitled in exchange for the sale of our products. This amount includes both fixed and variable consideration and excludes amounts that are collected from customers and remitted to governmental authorities, such as value-added taxes in foreign jurisdictions. Shipping and handling costs associated with outbound freight after control of a product has transferred to our customers are accounted for as a fulfillment cost and are included in operating expenses. The cost for any shipping and handling activities (including customs clearance activities) associated with transactions for which revenue has been recognized are accrued if not completed before the respective period end.

The timing between the recognition of revenue for product sales and the receipt of payment is not significant. Our standard credit terms, which vary based on the country of sale, range from 30 to 120 days and all arrangements are payable within one year of the transfer of the product. We do not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between the transfer of the promised good to the customer and receipt of payment will be one year or less.

Variable Consideration

We pay distribution fees to our distributors and offer rebates and/or discounts, or enter into volume-based reimbursement arrangements with certain customers. We reduce the transaction price on our sales for these amounts. For variable amounts, we estimate the amount of consideration to which we expect to be entitled based on all available historic, current and forecast information. We primarily use the expected value method to estimate variable payments and, in limited circumstances, will apply the most likely method based on the type of variable consideration and what method better predicts the amount of consideration we expect to be entitled to. Consideration that is received from a customer that we expect will need to be refunded in the future is recorded as a refund liability to the customer within accrued expenses. Actual amounts of consideration ultimately received or refunded may differ from our estimates. If actual results in the future vary from our estimates, we adjust these estimates, which would affect net product sales and earnings in the period such variances become known.

Variability in the transaction price for our products pursuant to our contracts with customers primarily arises from the following:

Discounts and Rebates: We offer discounts and rebates to certain distributors and customers under our arrangements. In many cases, these amounts are fixed at the time of sale and the transaction price is reduced accordingly. We also provide for rebates under certain governmental programs, including Medicaid in the U.S. and other programs outside the U.S., which are payable based on actual claim data. We estimate these rebates based on an analysis of historical claim patterns and estimates of customer mix to determine which sales will be subject to rebates and the amount of such rebates. We update our estimates and assumptions each period and record any necessary adjustments, which may have an impact on revenue in the period in which the adjustment is made. Generally, the length of time between product sale and the processing and reporting of the rebates is three to six months.

Volume-Based Arrangements: We have entered into volume-based arrangements with governments in certain countries and other customers in which reimbursement is limited to a contractual amount. Under this type of arrangement, amounts billed in excess of the contractual limitation are repaid to the customer as a rebate. We estimate incremental discounts resulting from these contractual limitations, based on forecasted sales during the limitation period, and we apply the discount percentage to product shipments as a reduction of revenue. Our calculations related to these arrangements require estimation of sales during the limitation period, and adjustments in these estimates may have a material impact in the period in which these estimates change.

Distribution & Other Fees: We pay distribution and other fees to certain customers in connection with the sales of our products. We record distribution and other fees paid to our customers as a reduction of revenue, unless the payment is for a distinct good or service from the customer and we can reasonably estimate the fair value of the goods or services received. If both conditions are met, we record the consideration paid to the customer as an operating expense. These costs are typically known at the time of sale, resulting in minimal adjustments subsequent to the period of sale.

Product Returns: Our contracts with customers generally provide for returns only if the product is damaged or defective upon delivery. We assess our sales transactions and arrangements with customers and monitor inventory within our sales channels to determine whether a provision for returns is warranted and a resulting adjustment to the transaction price is necessary. This assessment is based on historical experience and assumptions as of the date of sale and changes in these estimates could have an impact in the period in which the change occurs. Because of factors such as the price of our products, the limited number of patients, the short period from product sale to patient infusion and limited contractual return rights, our customers often carry limited inventory.

The amount of variable consideration included in the transaction price is constrained by the amount that is probable will not result in a significant reversal of revenue. We consider our experience with similar transactions and expectations regarding the contract in estimating the amount of variable consideration to which we expect to be entitled, and determining whether the estimated variable consideration should be constrained. We do not have any material constraints on the variable consideration included within the transaction price of our current revenue arrangements.

See Note 19, Segment Information for a summary of revenue from contracts with customers by product and geographical region.

Contract Balances and Receivables

Contract liabilities relate to consideration received and/or billed for goods that have not been delivered to the customer and for which the performance obligation has not yet been completed. These amounts are included within other current liabilities in the consolidated statements of operations.

The following table provides information about receivables and contract liabilities from our contracts with customers.



	December 31, 2019		December 31, 2018
Receivables, which are included in "Trade accounts receivable, net"	$	1,243.2	$	922.3
Contract liabilities, which are included in "Other current liabilities"	$	6.8	$	3.4

Research and Development Expenses

Research and development expenses are comprised of costs incurred in performing research and development activities including payroll and benefits, preclinical, clinical trial and related clinical manufacturing costs, manufacturing development and scale-up costs, product development and regulatory costs, contract services and other outside contractor costs, research license fees, depreciation and amortization of lab facilities, and lab supplies. These costs are expensed as incurred. We accrue costs for clinical trial activities based upon estimates of the services received and related expenses incurred that have yet to be invoiced by the contract research organizations, clinical study sites, laboratories, consultants, or other clinical trial vendors that perform the activities.

Share-Based Compensation

We have two share-based compensation plans pursuant to which awards are currently being made: (i) the 2017 Incentive Plan (2017 Plan) and (ii) the 2015 Employee Stock Purchase Plan (ESPP). The 2017 Plan replaced the Amended & Restated 2004 Incentive Plan (2004 Plan), effective May 10, 2017. Under the 2017 Plan, restricted stock, restricted stock units, stock options and other stock-related awards may be granted to our directors, officers, employees and consultants or advisors of the Company or any subsidiary. Under the ESPP, eligible employees can purchase shares of common stock at a discount semi-annually through payroll deductions. To date, share-based compensation issued under the plans consists of incentive and non-qualified stock options, restricted stock and restricted stock units, including restricted stock units with market and non-market performance conditions, and shares issued under our ESPP.

Compensation expense for our share-based awards is recognized based on the estimated fair value of the awards on the grant date. Compensation expense reflects an estimate of the number of awards expected to vest and is primarily recognized on a straight-line basis over the requisite service period of the individual grants, which typically equals the vesting period. Compensation expense for awards with performance conditions is recognized using the graded-vesting method.

Our estimates of employee stock option values rely on estimates of factors we input into the Black-Scholes model. The key factors involve an estimate of future uncertain events. Assumptions include the use of historical volatility to determine the expected stock price volatility. We also estimate expected term until exercise and the reduction in the expense from expected forfeitures. We currently use historical exercise and cancellation patterns as our best estimate of future estimated life.

For our non-market performance-based awards, we estimate the anticipated achievement of the performance targets, including forecasting the achievement of future financial targets. These estimates are revised periodically based on the probability of achieving the performance targets and adjustments are made throughout the performance period as necessary. We use payout simulation models to estimate the grant date fair value of awards with market-based performance conditions. The payout simulation models assume volatility of our common stock and the common stock of a comparator group of companies, as well as correlations of returns of the price of our common stock and the common stock prices of the comparator group.

The purchase price of common stock under our ESPP is equal to 85.0% of the lower of (i) the market value per share of the common stock on the first business day of an offering period or (ii) the market value per share of the common stock on the purchase date. The fair value of the discounted purchases made under our ESPP is calculated using the Black-Scholes model. The fair value of the look-back provision plus the 15.0% discount is recognized as compensation expense over the 6 month purchase period.

Restructuring and Restructuring Related Expenses

We record liabilities associated with one-time employee termination benefits and exit or disposal activities in the period in which the liability is incurred. One-time employee benefits are incurred when communicated to employees and / or where detailed action plans have been approved. For existing benefit arrangements, employee termination costs are accrued when the exit or disposal cost are probable and estimable. Costs for one-time termination benefits in which the employee is required to render service until termination in order to receive benefits are recognized ratably over the service period.

Restructuring related expenses include accelerated depreciation costs and impairment charges associated with assets impacted by a restructuring exit activity. Accelerated depreciation costs represent the difference between the depreciation expense recognized over the revised useful life of the asset, based upon the anticipated date an impacted site closure, and the depreciation expense as determined using the useful life prior to the restructuring activities.

Earnings Per Common Share

Basic earnings per common share (EPS) is computed by dividing net income by the weighted-average number of shares of common stock outstanding. For purposes of calculating diluted EPS, the denominator reflects the potential dilution that could occur if stock options, unvested restricted stock units or other contracts to issue common stock were exercised or converted into common stock, using the treasury stock method.

The following table summarizes the calculation of basic and diluted EPS for years ended December 31, 2019, 2018 and 2017:



	Year Ended December 31,
	2019		2018		2017
Net income used for basic and diluted calculation	$	2,404.3	$	77.6	$	443.3
Shares used in computing earnings per common share—basic	223.2		222.7		223.9
Weighted-average effect of dilutive securities:
Stock awards	1.6		1.8		1.5
Shares used in computing earnings per common share—diluted	224.8		224.5		225.4
Earnings per common share:
Basic	$	10.77	$	0.35	$	1.98
Diluted	$	10.70	$	0.35	$	1.97

We exclude from EPS the weighted-average number of securities whose effect is anti-dilutive. Excluded from the calculation of EPS for the years ended December 31, 2019, 2018 and 2017 were 3.0, 2.8, and 4.0 shares of common stock, respectively, because their effect is anti-dilutive.

Income Taxes

We utilize the asset and liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement carrying amounts and tax basis of assets and liabilities using enacted tax rates in effect for years in which the temporary differences are expected to reverse. We periodically evaluate the likelihood of the realization of deferred tax assets and reduce the carrying amount of these deferred tax assets by a valuation allowance when it is more likely than not that deferred tax assets will not be realized.

We recognize the benefit of an uncertain tax position that has been taken or we expect to take on income tax returns if such tax position is more likely than not to be sustained. The tax benefit recognized in the financial statements for a particular tax position is based on the largest benefit that is more likely than not to be realized. The amount of unrecognized tax benefits is adjusted, as appropriate, for changes in facts and circumstances, such as significant amendments to existing tax law, new regulations or interpretations by the taxing authorities, or new information obtained during a tax examination or resolution of an examination. We also accrue for potential interest and penalties related to unrecognized tax benefits as a component of tax expense.

structure, which derives income from multiple jurisdictions, requires us to interpret the related tax laws and regulations within those jurisdictions and develop estimates and assumptions regarding significant future events, such as the amount, timing and character of deductions and the applicability of foreign tax credits. From time to time, we execute intercompany transactions that may impact the valuation of the captive foreign partnership and the corresponding interest allocated to each partner, resulting in a change to deferred taxes. The transactions and related valuations require the application of transfer pricing guidelines issued by the relevant taxing authorities. Significant estimates and assumptions within discounted cash flow models are also required to calculate the valuations.

In December 2017, the Tax Cuts and Jobs Act (Tax Act) was enacted into law. The Tax Act decreased the U.S. federal corporate tax rate to 21.0%, imposed a minimum tax on foreign earnings related to intangible assets (GILTI), a one-time transition tax on previously unremitted foreign earnings, and modified the taxation of other income and expense items. With regard to the GILTI minimum tax, foreign earnings are reduced by the profit attributable to tangible assets and a deductible allowance of up to 50.0%, subject to annual limitations. We have elected to account for the impact of the minimum tax in deferred taxes.

Comprehensive Income

Comprehensive income is comprised of net income and other comprehensive income (loss). Other comprehensive income (loss) includes changes in equity that are excluded from net income, such as changes in pension liabilities, unrealized gains and losses on marketable debt securities, unrealized gains and losses on hedge contracts and foreign currency translation adjustments. These changes in equity are reflected net of tax.

Reclassifications

Certain items in the prior year’s consolidated financial statements have been reclassified to conform to the current presentation.

New Accounting Pronouncements

Accounting Standards Update (ASU) 2016-13, "Measurement of Credit Losses on Financial Instruments": In June 2016, the Financial Accounting Standards Board (FASB) issued a new standard intended to improve reporting requirements specific to loans, receivables and other financial instruments. The new standard requires that credit losses on financial assets measured at amortized cost be determined using an expected loss model, instead of the current incurred loss model, and requires that credit losses related to available-for-sale debt securities be recorded through an allowance for credit losses and limited to the amount by which carrying value exceeds fair value. The new standard also requires enhanced disclosure of credit risk associated with financial assets. The standard is effective for interim and annual periods beginning after December 15, 2019 with early adoption permitted.

We adopted the new standard on January 1, 2020 and have substantially completed our assessment of the standard based on the composition of our portfolio of financial instruments and current and forecasted economic conditions as of January 1, 2020. We are continuing to finalize our calculations for credit losses and to establish processes and internal controls that may be required to comply with the new credit loss standard and related disclosure requirements. We do not expect the adoption of this standard to have a significant impact on our consolidated financial statements.

ASU 2018-15, "Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract": In August 2018, the FASB issued a new standard on a customer's accounting for implementation, set-up, and other upfront costs incurred in a cloud computing arrangement (CCA) that aligns the requirements for capitalizing implementation costs in a CCA service contract with existing internal-use software guidance. The standard also provides classification guidance on these implementation costs as well as additional quantitative and qualitative disclosures. The standard is effective for interim and annual periods beginning after December 15, 2019, with early adoption permitted, and can be adopted prospectively or retrospectively.

We adopted the new standard on January 1, 2020 on a prospective basis and are continuing to establish new processes and internal controls that may be required to comply with the new cloud computing standard. We do not expect the adoption of this standard to have a significant impact on our financial statements; however, the adoption of this standard will result in an increase in capitalized assets related to qualifying CCA implementation costs incurred after the adoption date.

ASU 2019-12, “Income Taxes: Simplifying the Accounting for Income Taxes”: In December 2019, the FASB issued a new standard intended to simplify the accounting for income taxes by eliminating certain exceptions

related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. The new guidance also simplifies aspects of the accounting for franchise taxes and enacted changes in tax laws or rates and clarifies the accounting for transactions that result in a step-up in the tax basis of goodwill. The standard is effective for annual periods beginning after December 15, 2020 and interim periods within, with early adoption permitted. Adoption of the standard requires certain changes to be made prospectively, with some changes to be made retrospectively. We are currently assessing the impact of this standard on our financial condition and results of operations.

ASU 2020-01, “Investments - Equity Securities, Investments - Equity Method and Joint Ventures, and Derivatives and Hedging - Clarifying the Interactions Between Topic 321, Topic 323, and Topic 815”: In January 2020, the FASB issued a new standard intended to clarify the interactions between ASC 321, ASC 323 and ASC 815. The new standard addresses accounting for the transition into and out of the equity method and measurement of certain purchased options and forward contracts to acquire investments. The standard is effective for annual and interim periods beginning after December 15, 2020, with early adoption permitted. Adoption of the standard requires changes to be made prospectively. We are currently assessing the impact of this standard on our financial condition and results of operations.

Recently Adopted Accounting Pronouncements

ASU 2016-02, “Leases”: In February 2016, the FASB issued a new standard that requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. The new standard establishes a right of use (ROU) model that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. Leases will be classified as financing or operating, with classification affecting the pattern and classification of expense recognition in the statement of operations.

We adopted the new standard on January 1, 2019 using the modified retrospective approach. We have elected to apply the transition method that allows companies to continue applying the guidance under the lease standard in effect at that time in the comparative periods presented in the consolidated financial statements and recognize a cumulative-effect adjustment to the opening balance of retained earnings on the date of adoption. We also elected the “package of practical expedients”, which permits us not to reassess under the new standard our prior conclusions about lease identification, lease classification and initial direct costs.

Results for reporting periods beginning on or after January 1, 2019 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for the prior period. Upon adoption of the new lease standard, on January 1, 2019, we derecognized $472.8 of property, plant and equipment and other assets and $372.2 of facility lease obligations associated with previously existing build-to-suit arrangements. We capitalized ROU assets of $326.1, inclusive of opening adjustments of $70.8 primarily related to prepaid rent existing at transition, and $255.3 of lease liabilities, within our consolidated balance sheets upon adoption. At transition, we recorded a decrease of $90.3 to retained earnings, net of tax, primarily related to our derecognition of previously recorded build-to-suit arrangements.

ASU 2018-02, "Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income": In February 2018, the FASB issued a new standard that permits entities to make a one-time reclassification from accumulated other comprehensive income (AOCI) to retained earnings for the stranded tax effects resulting from the newly enacted corporate tax rates under the Tax Cuts and Jobs Act (the Tax Act) that was effective for the year ended December 31, 2017. We adopted the new standard on January 1, 2019 and elected not to reclassify the income tax effects of the Tax Act from AOCI to retained earnings. We continue to release disproportionate income tax effects from AOCI based on the aggregate portfolio approach. The adoption of this standard did not have an impact on our consolidated financial statements.

Acquisitions

12 Months Ended

Dec. 31, 2019

Business Combinations [Abstract]

Acquisitions

Wilson Therapeutics AB

On May 25, 2018, we completed the acquisition of Wilson Therapeutics AB (publ), a biopharmaceutical company based in Stockholm, Sweden (Wilson Therapeutics) that developed a novel therapy for patients with rare copper-mediated disorders, pursuant to a recommended public cash offer of SEK 232 for each share of stock of Wilson Therapeutics. As a result of the acquisition, we added WTX101 (ALXN1840), a highly innovative drug candidate that is currently in Phase III clinical trials for the treatment of patients with Wilson disease, to our clinical pipeline.

The acquisition of Wilson Therapeutics was accounted for as an asset acquisition, as substantially all of the fair value of the gross assets acquired was concentrated in a single asset, WTX101.

The following table summarizes the total consideration for the acquisition and the value of assets acquired and liabilities assumed:



Consideration
Cash paid for acquisition of Wilson Therapeutics outstanding shares	$	749.3
Transaction costs	15.1
Total consideration	$	764.4

Assets Acquired and Liabilities Assumed
Cash	$	45.1
In-process research & development	803.7
Employee related liabilities	(71.4		)
Other assets and liabilities	(13.0		)
Total net assets acquired	$	764.4

The acquired in-process research and development asset relates to WTX101. Due to the stage of development of this asset at the date of acquisition, significant risk remained and it was not yet probable that there was future economic benefit from this asset. Absent successful clinical results and regulatory approval for the asset, there was no alternative future use associated with WTX101. Accordingly, the value of this asset was expensed during the second quarter of 2018.

Employee related liabilities include the value of outstanding employee equity incentive awards that were accelerated in connection with the Wilson Therapeutics acquisition that have been settled in cash. Also included in this amount were employer tax obligations associated with the employee equity incentive awards.

In connection with rights to WTX101 that were previously acquired by Wilson Therapeutics from third parties, we could be required to pay up to approximately $19.0 if certain development, regulatory and commercial milestones are met over time, as well as royalties on commercial sales.

Syntimmune, Inc.

In September 2018, we entered into a definitive agreement to acquire Syntimmune, Inc. (Syntimmune), a clinical-stage biotechnology company developing an antibody therapy targeting the FcRn. Syntimmune’s lead candidate, SYNT001 (ALXN1830), is a monoclonal antibody that is designed to inhibit the interaction of FcRn with Immunoglobulin G (IgG) and IgG immune complexes, that is being studied for the treatment of IgG-mediated autoimmune diseases. The acquisition of Syntimmune closed in November 2018. Under the terms of the acquisition agreement, Alexion acquired Syntimmune for an upfront cash payment of $400.0, with the potential for additional milestone-dependent payments of up to $800.0, for a total potential value of up to $1,200.0.

The acquisition of Syntimmune was accounted for as an asset acquisition, as substantially all of the fair value of the gross assets acquired was concentrated in a single in-process research and development asset, SYNT001.

In connection with the agreement of the final working capital adjustment for the Syntimmune acquisition, we recognized a benefit of $4.1 associated with previously acquired in-process research and development in the second quarter 2019.

The following table summarizes the total consideration for the acquisition and the value of the assets acquired and liabilities assumed:



Consideration
Upfront payment for acquisition of Syntimmune outstanding shares	$	400.0
Cash acquired	4.2
Working capital adjustment	2.3
Transaction costs	0.9
Total consideration	$	407.4

Assets Acquired and Liabilities Assumed
Cash	$	4.2
In-process research & development	375.2
Deferred tax assets	25.1
Other assets and liabilities	2.9
Total net assets acquired	$	407.4

The acquired in-process research and development asset relates to SYNT001. Due to the stage of development of this asset at the date of acquisition, significant risk remained and it was not yet probable that there was future economic benefit from this asset. Absent successful clinical results and regulatory approval for the asset, there was no alternative future use associated with SYNT001. Accordingly, the value of this asset was expensed during the fourth quarter of 2018.

Achillion Pharmaceuticals, Inc.

In October 2019, Alexion entered into a definitive agreement to acquire Achillion Pharmaceuticals, Inc. (Achillion), a clinical-stage biopharmaceutical company focused on the development of oral Factor D inhibitors. Achillion is developing oral small molecule Factor D inhibitors to treat people with complement alternative pathway-mediated rare diseases, such as PNH and C3 glomerulopathy (C3G). The company currently has two clinical stage medicines in development, including danicopan (ACH-4471) and ACH-5228.

The acquisition of Achillion closed on January 28, 2020 . Under the terms of the agreement, we acquired all outstanding common stock of Achillion for $6.30 per share, or approximately $926.0, inclusive of the settlement of Achillion’s outstanding equity awards. The acquisition was funded with cash on hand. The transaction includes the potential for additional consideration in the form of non-tradeable contingent value rights (CVRs), which will be paid to Achillion shareholders if certain clinical and regulatory milestones are achieved within specified periods. These include $1.00 per share for the U.S. FDA approval of danicopan and $1.00 per share for the initiation of Phase 3 in ACH-5228.

We anticipate accounting for the transaction as a business combination and are currently evaluating the purchase price allocation. Due to the proximity of the completion of the acquisition to the filing of this Form 10-K, it is not practicable to provide a preliminary purchase price allocation of the fair value of the assets purchased and liabilities assumed in the transaction. The Company expects to finalize the valuation and complete the preliminary purchase price allocation in the first quarter of 2020.

Property, Plant and Equipment, Net

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment, Net [Abstract]

Property, Plant and Equipment, Net

A summary of property, plant and equipment is as follows:



	December 31, 2019			December 31, 2018
Land	$	9.6		$	9.6
Buildings and improvements	208.7			520.1
Machinery and laboratory equipment	126.0			161.7
Computer hardware and software	155.1			144.8
Furniture and office equipment	23.4			27.5
Construction-in-progress	734.2			827.1
Financing lease right of use assets	127.2			—
	1,384.2			1,690.8
Less: Accumulated depreciation and amortization	(220.9		)	(219.3		)
	$	1,163.3		$	1,471.5

On January 1, 2019, we adopted a new lease accounting standard and results for reporting periods beginning on January 1, 2019 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for the prior period. Upon adoption of the new lease standard, on January 1, 2019, we derecognized $472.8 of property, plant and equipment and other assets associated with previously existing build-to-suit arrangements. See Note 1, Business Overview & Summary of Significant Accounting Policies for an overview of the impact this standard had on our property, plant and equipment balances upon adoption. Financing lease right of use assets recorded as a result of the new standard are included in property, plant and equipment in our consolidated balance sheet as of December 31, 2019.

Depreciation and amortization of property, plant and equipment was approximately $56.8, $77.9 and $95.8 recorded within our consolidated statement of operations for the years ended December 31, 2019, 2018 and 2017, respectively. Included within this amount for the years ended December 31, 2018 and 2017 were charges related to the 2017 restructuring activities. See Note 18, Restructuring and Related Expenses for additional information.

At December 31, 2019 and 2018, computer software costs included in property, plant and equipment were $53.4 and $50.3, respectively. Depreciation and amortization expense for capitalized computer software costs was $15.3, $17.4 and $16.0 for the years ended December 31, 2019, 2018 and 2017, respectively.

Intangible Assets and Goodwill

12 Months Ended

Dec. 31, 2019

Finite-Lived Intangible Assets [Line Items]

Intangible Assets and Goodwill

The following table summarizes the carrying amount of our intangible assets and goodwill, net of accumulated amortization:



		December 31, 2019							December 31, 2018
	Estimated Life (years)	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net
Licensing Rights	3-8	$	57.0	$	(34.7	)	$	22.3	$	39.0	$	(29.3	)	$	9.7
Patents	7	10.5		(10.5		)	—		10.5		(10.5		)	—
Purchased technology	6-16	4,710.5		(1,388.7		)	3,321.8		4,710.5		(1,079.1		)	3,631.4
Other Intangibles	5	0.4		(0.2		)	0.2		0.4		(0.2		)	0.2
Total		$	4,778.4	$	(1,434.1	)	$	3,344.3	$	4,760.4	$	(1,119.1	)	$	3,641.3
Goodwill	Indefinite	$	5,040.3	$	(2.9	)	$	5,037.4	$	5,040.3	$	(2.9	)	$	5,037.4

During 2019 and 2018, we capitalized $18.0 and $8.0, respectively, related to regulatory approval and commercial milestones related to in-licensing arrangements.

During the third quarter 2019, the U.S. patent term extension to a composition of matter patent for STRENSIQ was granted, which resulted in an increase in the estimated useful life of the STRENSIQ intangible asset and will result in lower amortization expense in future periods.

Amortization expense was $315.0, $321.1 and $320.2 for the years ended December 31, 2019, 2018 and 2017, respectively. Assuming no changes in the gross cost basis of intangible assets, the total estimated amortization expense for finite-lived intangible assets is approximately $298.0 for each of the years ending December 31, 2020 through December 31, 2024.

As of December 31, 2019, the net book value of our purchased technology includes $2,992.4 associated with the KANUMA intangible asset, which we acquired in the acquisition of Synageva BioPharma Corp. As part of our standard quarterly procedures, we reviewed the KANUMA asset as of December 31, 2019 and determined that there were no indicators of impairment. Cash flow models used in our assessments are based on our commercial experience to date with KANUMA and require the use of significant estimates, which include, but are not limited to, long-range pricing expectations and patient-related assumptions, including patient identification, conversion and retention rates. We will continue to review the related valuation and accounting of this asset as new information becomes available to us.

Marketable Securities

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

The amortized cost, gross unrealized holding gains, gross unrealized holding losses and fair value of available-for-sale debt securities by type of security at December 31, 2019 and December 31, 2018 were as follows:



	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
Commercial paper	$	246.9	$	—	$	—	$	246.9
Corporate bonds	24.3		—		—		24.3
Other government related obligations:
U.S.	70.4		—		—		70.4
Bank certificates of deposit	27.4		—		—		27.4
Total available-for-sale debt securities	$	369.0	$	—	$	—	$	369.0



	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Commercial paper	$	52.1	$	—	$	—		$	52.1
Corporate bonds	122.9		—		(0.1		)	122.8
Other government related obligations:
U.S.	17.5		—		—			17.5
Bank certificates of deposit	33.2		—		—			33.2
Total available-for-sale debt securities	$	225.7	$	—	$	(0.1	)	$	225.6

The aggregate fair value of available-for-sale debt securities in an unrealized loss position as of December 31, 2019 and December 31, 2018 was $21.5 and $128.7, respectively. We did not have any investments in a continuous unrealized loss position for more than twelve months as of December 31, 2019 and December 31, 2018. As of December 31, 2019, we believe that the cost basis of our available-for-sale debt securities is recoverable.

The fair values of available-for-sale debt securities by classification in the consolidated balance sheet were as follows:



	December 31, 2019		December 31, 2018
Cash and cash equivalents	$	328.1	$	43.8
Marketable securities	40.9		181.8
	$	369.0	$	225.6

The fair values of available-for-sale debt securities as of December 31, 2019, by contractual maturity, are summarized as follows:



	December 31, 2019
Due in one year or less	$	365.5
Due after one year through three years	3.5
Due after three years through five years	—
	$	369.0

We sponsor a nonqualified deferred compensation plan which allows certain highly-compensated employees to elect to defer income to future periods. Participants in the plan earn a return on their deferrals based on several investment options, which mirror returns on underlying mutual fund investments. We choose to invest in the underlying mutual fund investments to offset the liability associated with our nonqualified deferred compensation plan. These mutual fund investments are valued at net asset value per share and are carried at fair value with gains and losses included in investment income. The changes in the underlying liability to the employee are recorded in operating expenses. As of December 31, 2019 and December 31, 2018, the fair value of these investments was $23.1 and $16.5, respectively.

We utilize the specific identification method in computing realized gains and losses. Realized gains and losses on our marketable securities were not material for the years ended December 31, 2019, 2018 and 2017.

Derivative Instruments and Hedging Activities

12 Months Ended

Dec. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments and Hedging Activities

We operate internationally and, in the normal course of business, are exposed to fluctuations in foreign currency exchange rates. The exposures result from portions of our revenues, as well as the related receivables, and expenses that are denominated in currencies other than the U.S. dollar, primarily the Euro and Japanese Yen. We are also exposed to fluctuations in interest rates on outstanding borrowings under our revolving credit facility, if any, and term loan facility. We manage these exposures within specified guidelines through the use of derivatives. All of our derivative instruments are utilized for risk management purposes, and we do not use derivatives for speculative trading purposes.

We enter into foreign exchange forward contracts, with durations of up to 60 months, to hedge exposures resulting from portions of our forecasted revenues, including intercompany revenues, and certain forecasted expenses that are denominated in currencies other than the U.S. dollar. The purpose of these hedges is to reduce the volatility of exchange rate fluctuations on our operating results. These hedges are designated as cash flow hedges upon contract inception. As of December 31, 2019, we had open revenue related foreign exchange forward contracts with notional amounts totaling $1,089.9 that qualified for hedge accounting with current contract maturities through June 2021. As of December 31, 2019, we had open expense related foreign exchange forward contracts with notional amounts totaling $14.0 that qualified for hedge accounting with contract maturities through September 2022.

To achieve a desired mix of floating and fixed interest rates on our term loan, we enter into interest rate swap agreements that qualify for and are designated as cash flow hedges. These contracts convert the floating interest rate on a portion of our debt to a fixed rate, plus a borrowing spread.

The following table summarizes the total interest rate swap contracts executed as of December 31, 2019:



Type of Interest Rate Swap	Notional Amount	Effective Date	Termination Date	Fixed Interest Rate or Rate Range
Floating to Fixed	450.0	December 2018	December 2022	2.60% - 2.79%
Floating to Fixed	1,300.0	December 2019	December 2022	2.37% - 2.83%

The amount of gains and (losses) recognized in the consolidated statements of operations for the years ended December 31, 2019, 2018, and 2017 from foreign exchange and interest rate swap contracts that qualified as cash flow hedges were as follows:



	Year ended December 31,
	2019					2018						2017
Financial Statement Line Item in which the Effects of Cash Flow Hedges are Recorded	Net Product Sales		Interest Expense			Net Product Sales			Interest Expense			Net Product Sales		Interest Expense
Total amount presented in the Consolidated Statements of Operations	$	4,990.0	$	(77.8	)	$	4,130.1		$	(98.2	)	$	3,549.5	$	(98.4	)
Impact of cash flow hedging relationships:
Foreign exchange forward contracts	$	36.8	$	—		$	(1.8	)	$	—		$	28.9	$	—
Interest rate swap contracts	$	—	$	13.3		$	—		$	13.6		$	—	$	(1.8	)

The impact on accumulated other comprehensive income (AOCI) and earnings from foreign exchange and interest rate swap contracts that qualified as cash flow hedges, for the years ended December 31, 2019, 2018, and 2017 were as follows:



	Year Ended December 31,
	2019			2018			2017
Foreign Exchange Forward Contracts:
Gain (loss) recognized in AOCI, net of tax	$	27.9		$	37.7		$	(96.1	)
Gain (loss) reclassified from AOCI to net product sales, net of tax	$	28.4		$	(1.4	)	$	18.7
Interest Rate Swap Contracts:
Gain (loss) recognized in AOCI, net of tax	$	(39.0	)	$	(4.8	)	$	7.9
Gain (loss) reclassified from AOCI to interest expense, net of tax	$	10.2		$	10.8		$	(1.1	)

Assuming no change in foreign exchange rates from market rates at December 31, 2019, $6.7 of gains recognized in AOCI will be reclassified to revenue over the next 12 months. Assuming no change in LIBOR-based interest rates from market rates at December 31, 2019, $19.5 of losses recognized in AOCI will be reclassified to interest expense over the next 12 months. Amounts recognized in AOCI for expense related foreign exchange forward contracts were immaterial as of December 31, 2019.

We enter into foreign exchange forward contracts, with durations of up to 8 months, designed to limit the balance sheet exposure of monetary assets and liabilities. We enter into these hedges to reduce the impact of fluctuating exchange rates on our operating results. Hedge accounting is not applied to these derivative instruments as gains and losses on these hedge transactions are designed to offset gains and losses on underlying balance sheet exposures. As of December 31, 2019, the notional amount of foreign exchange contracts where hedge accounting is not applied was $1,974.6.

We recognized a (loss) gain of $(0.4), $23.0 and $(14.7), in other income and (expense) for the years ended December 31, 2019, 2018 and 2017, respectively, associated with the foreign exchange contracts not designated as hedging instruments. These amounts were partially offset by gains or losses on monetary assets and liabilities.

The following tables summarize the fair value of outstanding derivatives at December 31, 2019 and 2018:



	December 31, 2019
	Asset Derivatives			Liability Derivatives
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Derivatives designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	$	12.7	Other current liabilities	$	6.2
Foreign exchange forward contracts	Other assets	0.6		Other liabilities	1.1
Interest rate contracts	Prepaid expenses and other current assets	—		Other current liabilities	19.5
Interest rate contracts	Other assets	—		Other liabilities	41.9
Derivatives not designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	17.2		Other current liabilities	20.4
Total fair value of derivative instruments		$	30.5		$	89.1



	December 31, 2018
	Asset Derivatives			Liability Derivatives
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Derivatives designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	$	16.9	Other current liabilities	$	7.3
Foreign exchange forward contracts	Other assets	0.3		Other liabilities	3.1
Interest rate contracts	Prepaid expenses and other current assets	20.1		Other current liabilities	0.8
Interest rate contracts	Other assets	—		Other liabilities	17.3
Derivatives not designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	23.6		Other current liabilities	11.5
Total fair value of derivative instruments		$	60.9		$	40.0

Although we do not offset derivative assets and liabilities within our consolidated balance sheets, our International Swap and Derivatives Association agreements provide for net settlement of transactions that are due to or from the same counterparty upon early termination of the agreement due to an event of default or other termination event. The following tables summarize the potential effect on our condensed consolidated balance sheets of offsetting our foreign exchange forward contracts and interest rate contracts subject to such provisions:



December 31, 2019
								Gross Amounts Not Offset in the Consolidated Balance Sheet
Description	Gross Amounts of Recognized Assets/Liabilities			Gross Amounts Offset in the Consolidated Balance Sheet	Net Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheet			Derivative Financial Instruments			Cash Collateral Received (Pledged)		Net Amount
Derivative assets	$	30.5			$	30.5		$	(21.4	)	$	—	$	9.1
Derivative liabilities	$	(89.1	)		$	(89.1	)	$	21.4		$	—	$	(67.7	)



December 31, 2018
									Gross Amounts Not Offset in the Consolidated Balance Sheet
Description	Gross Amounts of Recognized Assets/Liabilities			Gross Amounts Offset in the Consolidated Balance Sheet		Net Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheet			Derivative Financial Instruments			Cash Collateral Received (Pledged)		Net Amount
Derivative assets	$	60.9		$	—	$	60.9		$	(30.2	)	$	—	$	30.7
Derivative liabilities	$	(40.0	)	$	—	$	(40.0	)	$	30.2		$	—	$	(9.8	)

Other Investments	12 Months Ended
Other Investments	Dec. 31, 2019
Investments, All Other Investments [Abstract]
Other Investments	Other Investments Other investments include strategic investments in equity securities of certain biotechnology companies which we acquired in connection with license and option agreements. These investments are included in other assets in our consolidated balance sheets. Moderna During 2014, we purchased $37.5 of preferred stock of Moderna Therapeutics, Inc. (Moderna), a privately held biotechnology company, which was recorded at cost. During the first quarter 2018, Moderna announced the completion of a new round of financing. We considered this transaction and the rights of the new shares issued in the new round, compared to the rights of the preferred equity that we held, and concluded that Moderna’s new round of financing represented an observable price change in an orderly transaction for a similar investment. We further concluded, based on the respective rights of the stock and consideration of potential liquidity events, that the value of our preferred stock was equivalent to the value of the newly issued preferred stock. As a result, we recognized an unrealized gain of $100.8 in investment income during the first quarter 2018 to adjust our equity investment in Moderna to fair value as of the date of the observable price change, based on the per share price in Moderna's new round of financing. On December 6, 2018, Moderna completed its initial public offering (IPO) and shares of Moderna began trading on the Nasdaq Global Select Market under the symbol “MRNA.” As part of the IPO, our preferred stock was converted into Moderna common stock and subject to a one year lock-up period. As our equity investment in Moderna common stock now had a readily determinable fair value, we began to record the investment at fair value, with the effects of the holding period restriction estimated using an option pricing valuation model. During the fourth quarter 2018, we recognized an unrealized loss of $56.4 in investment income to adjust our investment in Moderna to fair value as of December 31, 2018. The fair value of this investment was $81.9 as of December 31, 2018. On December 9, 2019, we sold our investment in Moderna. We received $114.7 in net proceeds, resulting in a realized gain of $77.2 on our initial investment. During the twelve months ended December 31, 2019, we recognized a gain of $32.8 in investment income. Dicerna In October 2018, we purchased $10.3 of Dicerna Pharmaceuticals Inc. (Dicerna) common stock in connection with an agreement that we entered into with Dicerna, a publicly-traded biopharmaceutical company. As our equity investment in Dicerna common stock has a readily determinable fair value, we are recording the investment at fair value. During the twelve months ended December 31, 2019 and 2018, we recognized an unrealized gain of $9.5 and an unrealized loss of $1.4, respectively, in investment income to adjust our equity investment in Dicerna to fair value. The fair value of this investment was $18.4 and $8.9 as of December 31, 2019 and 2018, respectively. Caelum In January 2019, we purchased $41.0 of preferred stock of Caelum Biosciences (Caelum), a privately-held biotechnology company, and a $16.1 option to acquire the remaining equity in Caelum, based on Phase II data, in connection with an agreement that we entered into with Caelum. Following discussions with the FDA, Caelum changed the design of its clinical development program and now plans to initiate expanded Phase II/III trials in the second quarter 2020. In December 2019, we amended the terms of the agreement with respect to the option to acquire the remaining equity in Caelum based on data from the expanded Phase II/III trials. We accounted for the amendment as an exchange transaction as the terms of the modified option were determined to be substantially different than the terms of the original option. In conjunction with this amendment, we recognized a gain of $32.0 in other income and (expense), which reflects an increase in the fair value of the option, less $20.0 in incremental upfront funding and $4.1 associated with the change in the fair value of contingent payments which we also modified as part of the amendment, see Note 11, Commitments and Contingencies for additional information on the agreement. As our equity investment in Caelum and the option to acquire the remaining equity in Caelum do not have a readily determinable fair value, we only adjust the carrying value of the assets for impairment and any subsequent changes resulting from an observable price change in an orderly transaction for identical or similar equity securities of the same issuer. There were no observable price changes associated with these assets during the twelve months ended December 31, 2019. The carrying value of the investment and option of $41.0 and $64.0, respectively, were not impaired as of December 31, 2019. Zealand In March 2019, we purchased $13.8 of Zealand Pharma A/S (Zealand) common stock in connection with an agreement that we entered into with Zealand, a publicly-traded biopharmaceutical company based in Copenhagen, Denmark, see Note 11, Commitments and Contingencies for additional information on the agreement. As our equity investment in Zealand common stock has a readily determinable fair value, we are recording the investment at fair value. During the twelve months ended December 31, 2019, we recognized an unrealized gain of $14.7, in investment income to adjust our equity investment in Zealand to fair value as of December 31, 2019. The fair value of this investment was $28.5 as of December 31, 2019. Eidos In September 2019, we purchased $19.9 of Eidos Therapeutics, Inc. (Eidos) common stock, in connection with an agreement that we entered into with Eidos, a publicly-traded biopharmaceutical company and subsidiary of BridgeBio Pharma, Inc., see Note 11, Commitments and Contingencies for additional information on the agreement. As our equity investment in Eidos common stock has a readily determinable fair value, we are recording the investment at fair value, with the effects of a one year holding period restriction estimated using an option pricing valuation model. During the twelve months ended December 31, 2019, we recognized an unrealized gain of $7.9 in investment income to adjust our equity investment in Eidos to fair value as of December 31, 2019. The fair value of this investment was $27.8 as of December 31, 2019. Stealth In October 2019, we purchased $9.6 of Stealth BioTherapeutics Corp. (Stealth) common stock, in connection with an agreement that we entered into with Stealth, a publicly traded clinical-stage biotechnology company. See Note 11, Commitments and Contingencies for additional information on the agreement. As our equity investment in Stealth common stock has a readily determinable fair value, we are recording the investment at fair value. During the fourth quarter 2019, we recognized an unrealized loss of $5.2 in investment income to adjust our equity investment in Stealth to fair value as of December 31, 2019. The fair value of this investment was $4.4 as of December 31, 2019.

Accounts Payable and Accrued Expenses

12 Months Ended

Dec. 31, 2019

Accrued Liabilities [Abstract]

Accrued Expenses

Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consist of the following:



	December 31, 2019		December 31, 2018
Accounts Payable	$	74.0	$	74.4
Royalties	20.1		27.0
Payroll and employee benefits	191.3		170.4
Taxes payable	103.9		24.4
Rebates payable	250.1		122.8
Clinical	67.3		58.6
Manufacturing	72.8		72.0
Accrued restructuring costs	6.8		4.2
Other	180.4		144.4
	$	966.7	$	698.2

Debt

12 Months Ended

Dec. 31, 2019

Debt [Abstract]

Debt

On June 7, 2018, we entered into an Amended and Restated Credit Agreement (the Credit Agreement), with Bank of America, N.A. as Administrative Agent. The Credit Agreement amended and restated our credit agreement dated as of June 22, 2015 (the Prior Credit Agreement).

The Credit Agreement provides for a $1,000.0 revolving credit facility and a $2,612.5 term loan facility. The revolving credit facility and the term loan facility mature on June 7, 2023. Beginning with the quarter ending June 30, 2019, we are required to make payments of 5.00% of the original principal amount of the term loan facility annually, payable in equal quarterly installments.

Loans under the Credit Agreement bear interest, at our option, at either a base rate or a Eurodollar rate, in each case plus an applicable margin. Under the Credit Agreement, the applicable margins on base rate loans range from 0.25% to 1.00% and the applicable margins on Eurodollar loans range from 1.25% to 2.00%, in each case based on our consolidated net leverage ratio (as calculated in accordance with the Credit Agreement). At December 31, 2019, the interest rate on our outstanding loans under the Credit Agreement was 3.05%. Our obligations under the Credit Agreement are guaranteed by certain of Alexion Pharmaceuticals, Inc.'s foreign and domestic subsidiaries and secured by liens on certain of our subsidiaries’ equity interests, subject to certain exceptions. Under the terms of the Credit Agreement, we must maintain a ratio of total net debt to EBITDA of 3.50 to 1.00 (subject to certain limited adjustments) and EBITDA to cash interest expense ratio of at least 3.50 to 1.00, in each case as calculated in accordance with the Credit Agreement. We were in compliance with all applicable covenants under the Credit Agreement as of December 31, 2019.

The Credit Agreement contains certain representations and warranties, affirmative and negative covenants and events of default. The negative covenants in the Credit Agreement restrict Alexion’s and its subsidiaries’ ability, subject to certain baskets and exceptions, to (among other things) incur liens or indebtedness, make investments, enter into mergers and other fundamental changes, make dispositions or pay dividends. The restriction on dividend payments includes an exception that permits us to pay dividends and make other restricted payments regardless of dollar amount so long as, after giving pro forma effect thereto, we have a consolidated net leverage ratio, as defined in the Credit Agreement, within predefined ranges, subject to certain increases following designated material acquisitions.

In connection with entering into the Credit Agreement and the Prior Credit Agreement, we paid an aggregate of $53.1 in financing costs in 2018. Financing costs are amortized as interest expense over the life of the debt. Amortization expense associated with deferred financing costs for the years ended December 31, 2019, 2018, and 2017 was $5.0, $8.0, and $9.2, respectively. Remaining unamortized deferred financing costs as of December 31, 2019 and December 31, 2018 were $15.8 and $20.8, respectively.

We made principal payments of $98.0 on the term loan during 2019 and as of December 31, 2019, we had $2,514.5 outstanding on the term loan. In January 2019, we paid the outstanding balance on the revolving credit facility

of $250.0 in full, which was used to refinance amounts outstanding under the Prior Credit Agreement, and we had no outstanding borrowings under the revolving credit facility as of December 31, 2019. As of December 31, 2019, we had open letters of credit of $1.0 that offset our availability in the revolving facility.

The fair value of our long term debt, which is measured using Level 2 inputs of the fair value hierarchy, approximates book value.

The contractual maturities of our long-term debt obligations due subsequent to December 31, 2019 are as follows:



Year
2020	$	130.6
2021	130.6
2022	130.6
2023	2,122.7
2024	—

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

The following table summarizes our lease assets and liabilities as of December 31, 2019:



ROU Assets and Liabilities
	Balance Sheet Location	Financing		Operating
ROU - Asset	Right of use operating assets	$	—	$	204.0
ROU - Asset	Property, plant, and equipment	$	116.3	—
Lease liabilities (current)	Other current liabilities	$	5.2	18.8
Lease liabilities (noncurrent)	Noncurrent operating lease liabilities	$	—	164.1
Lease liabilities (noncurrent)	Other liabilities	$	72.9	—

The following table summarizes our lease related costs for the twelve months ended December 31, 2019:



Lease Cost
	Statement of Operations Location	Twelve months ended
		December 31, 2019
Financing Lease Cost		$	14.8
Amortization of ROU Assets	Operating Expenses	10.9
Interest on Lease Liabilities	Interest Expense	3.9
Operating Lease Cost	Operating Expenses	34.3
Variable Lease Cost	Operating Expenses	11.8
Total Lease Cost		$	60.9

Amounts above include $15.6 of lease costs associated with our CMO embedded lease arrangement for the twelve months ended December 31, 2019, which have been capitalized as part of the cost of product being manufactured at the site.

The following table summarizes supplemental cash flow information for the twelve months ended December 31, 2019:



Other Information
	Twelve months ended
	December 31, 2019
Cash Paid For Amounts Included In Measurement of Liabilities	$	32.3
Operating Cash Flows From Financing Leases	3.9
Operating Cash Flows From Operating Leases	23.5
Financing Cash Flows From Financing Leases	4.9
ROU Assets Obtained In Exchange For New Financing Liabilities ⁽¹⁾	—
ROU Assets Obtained In Exchange For New Operating Liabilities ⁽²⁾	27.5

(1) We capitalized $83.1 of ROU financing assets upon adoption of the new lease standard in the first quarter of 2019 that are excluded from the figures for the twelve months ended December 31, 2019. This figure excludes $44.2 of opening adjustments to ROU finance assets related, primarily, to prepayments of rent.
(2) We capitalized $172.2 of ROU operating assets upon adoption of the new lease standard in the first quarter of 2019 that are excluded from the figures for the twelve months ended December 31, 2019. This figure excludes $26.6 of opening adjustments to ROU operating assets related, primarily, to prepayments of rent.

The following tables summarize maturities of lease liabilities and the reconciliation of lease liabilities as of December 31, 2019:



Lease Liability Maturity Summary
Year	Financing		Operating		Total
2020	$	8.8	$	25.7	$	34.5
2021	9.0		23.0		32.0
2022	9.2		21.6		30.8
2023	9.2		20.9		30.1
2024	9.4		20.3		29.7
Thereafter	54.6		112.1		166.7



Reconciliation of Lease Liabilities	Financing			Operating			Total
Weighted-average Remaining Lease Term (years)	10.67			10.17			10.32
Weighted-average Discount Rate	4.85		%	4.10		%	4.33		%

Total Undiscounted Lease Liability	$	100.2		$	223.6		$	323.8
Imputed Interest	22.1			40.7			62.8
Total Discounted Lease Liability	78.1			182.9			261.0

For comparable purposes, our aggregate future minimum non-cancellable commitments under leases as of December 31, 2018 were as follows:



Year
2019	$	27.8
2020	24.7
2021	21.3
2022	19.9
2023	19.7
Thereafter	132.2

Excluded from the table above are commitments with Lonza Group AG and its affiliates (Lonza), a third party manufacturer that produces a portion of commercial and clinical quantities of our commercial products and product candidates. During the third quarter 2015, we entered into an agreement with Lonza whereby Lonza constructed a facility to be used to manufacture product under a supply agreement for Alexion at one of its existing facilities, resulting in the determination that the CMO arrangement contained a lease. This agreement requires us to make certain payments during the construction of the manufacturing facility and annual payments for ten years thereafter. As the arrangement contains both a lease and non-lease component, related to the supply of product, the consideration paid to Lonza is allocated between these components. As of December 31, 2018, we had various manufacturing and licensing agreements with Lonza, with remaining total non-cancellable future commitments of approximately $1,084.6. This amount included $88.7 of undiscounted, fixed payments applicable to our CMO embedded lease arrangement with Lonza, based on the relative standalone price of the lease and non-lease components of the arrangement at that time.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Asset Acquisition and In-License Agreements We have entered into asset purchase agreements, license agreements, and option arrangements in order to advance and obtain technologies and services related to our business. These agreements generally require us to pay an initial fee and certain agreements call for future payments upon the attainment of agreed upon development, regulatory and/or commercial milestones. These agreements may also require minimum royalty payments based on sales of products developed from the applicable technologies, if any. In January 2019, we entered into an agreement with Caelum, a biotechnology company that is developing CAEL101 for light chain (AL) amyloidosis. Under the terms of the agreement, we acquired a minority equity interest in preferred stock of Caelum and an exclusive option to acquire the remaining equity in Caelum based on Phase II data, for pre-negotiated economics. We paid $30.0 in the first quarter 2019 and agreed to pay up to an additional $30.0 in contingent development milestones prior to the exercise the option to acquire the remaining equity in Caelum. These contingent payments meet the definition of a derivative liability and were initially recorded at fair value of $27.1. We allocated the total consideration of $57.1, inclusive of the fair value of the contingent payments, to the equity investment in Caelum and the option to acquire the remaining equity in Caelum based on the relative fair values of the assets. Following discussions with the FDA, Caelum changed the design of its clinical development program and now plans to initiate expanded Phase II/III trials in the second quarter 2020. In December 2019, we amended the terms of the agreement with Caelum to modify the option to acquire the remaining equity in Caelum based on data from the expanded Phase II/III trials. The amendment also modified the development-related milestone events associated with the initial $30.0 in contingent payments, provided for an additional $20.0 in upfront funding, which we accrued as of December 31, 2019, as well as funding of $60.0 in exchange for an additional equity interest at fair value upon achievement of a specific development-related milestone event. The agreement with Caelum also provides for additional payments, in the event Alexion exercises the purchase option, for up to $500.0, which includes an upfront option exercise payment and potential regulatory and commercial milestone payments. In March 2019, we entered into an agreement with Zealand which provides us with exclusive worldwide licenses, as well as development and commercial rights, for subcutaneously delivered preclinical peptide therapies directed at up to four complement pathway targets. Pursuant to the agreement, Zealand will lead joint discovery and research efforts through the preclinical stage, and Alexion will lead development efforts beginning with the investigational new drug filing and Phase I studies. In addition to the agreement, we made an equity investment in Zealand (see Note 7, Other Investments). Under the terms of the agreement, we made an upfront payment of $40.0 for an exclusive license to the lead target and the equity investment, as well as for preclinical research services to be performed by Zealand in relation to the lead target. The market value of the equity investment was $13.8 as of the date of acquisition, which we recorded in other assets in our consolidated balance sheets. We also recognized prepaid research and development expense of $5.0 within the consolidated balance sheets associated with the research activities to be performed by Zealand. Due to the early stage of the asset we are licensing, we recorded the upfront license payment of $21.2 as research and development expense during the first quarter 2019. As of December 31, 2019, we could be required to pay up to $610.0, for the lead target, upon the achievement of specified development, regulatory and commercial milestones, as well as royalties on commercial sales. In addition, we could be required to pay up to an additional $115.0 in development and regulatory milestones if both a long-acting and short-acting product are developed with respect to the lead target. Each of the three subsequent targets can be selected for an option fee of $15.0 and has the potential for additional development, regulatory and commercial milestones, as well as royalty payments, at a reduced price to the lead target. In March 2019, we entered into an agreement with Affibody AB (Affibody), through which Alexion obtained an exclusive worldwide license, as well as development and commercial rights, to ABY-039, a bivalent antibody-mimetic that targets the FcRn and is currently in Phase I development. The agreement with Affibody was subject to clearance under the Hart-Scott Rodino Antitrust Improvements Act and, following receipt of such approval, the transaction closed in April 2019. Pursuant to the agreement, Alexion will lead the clinical development and commercial activities for ABY-039 in rare Immunoglobulin G (IgG)-mediated autoimmune diseases. Affibody has the option to co-promote ABY-039 in the U.S. and will lead clinical development of ABY-039 in an undisclosed indication. Under the terms of the agreement, we made an upfront payment of $25.0 for the exclusive license to ABY-039. Due to the early stage of the asset we are licensing, we recorded the upfront license payment as research and development expense during the second quarter 2019. As of December 31, 2019, we could also be required to pay up to $625.0 for amounts due upon achievement of specific development, regulatory, and commercial milestones, as well as royalties on commercial sales. In September 2019, we entered into an agreement with Eidos through which Alexion obtained an exclusive license to develop and commercialize AG10 in Japan. AG10 is a small molecule designed to treat the root cause of transthyretin amyloidosis (ATTR) and is currently in a Phase III study in the U.S. and Europe for ATTR cardiomyopathy (ATTR-CM). In addition, we made an equity investment in Eidos (see Note 7, Other Investments). Under the terms of the agreement, we made an upfront payment of $50.0 for the exclusive license to AG10 in Japan and the equity investment. The market value of the equity investment was $19.9 as of the date of acquisition, which we recorded in other assets in our consolidated balance sheets. Due to the early stage of the asset we are licensing, we recorded the upfront license payment of $30.1 as research and development expense during the third quarter 2019. As of December 31, 2019, we could also be required to pay $30.0 upon achievement of a Japanese-based regulatory milestone as well as royalties on commercial sales. In October 2019, we entered into an option agreement with Stealth BioTherapeutics Corp. (Stealth), a clinical-stage biotechnology company whose lead product candidate, elamipretide, is being investigated in late-stage clinical studies in three primary mitochondrial diseases - primary mitochondrial myopathy (PMM), Barth syndrome and Leber’s hereditary optic neuropathy (LHON). Under the terms of the agreement, we made an upfront payment of $30.0 for an equity investment in Stealth and an exclusive option to partner with Stealth in the development of subcutaneous elamipretide based on final results from the Phase III study in PMM. The market value of the equity investment was $9.6 as of the date of acquisition, which we recorded in other assets in our consolidated balance sheets. Due to the early stage of the asset for which we have an option to license, we recorded the upfront option payment of $20.4 as research and development expense during the fourth quarter 2019. In December 2019, Stealth announced that based on top-line data from the Phase 3 study in PMM, the study did not meet its primary endpoints. Following review of the Phase 3 data released in December 2019, we notified Stealth that we will not exercise the co-development option agreement. In October 2018, we entered into a collaboration agreement with Dicerna that provides us with exclusive worldwide licenses and development and commercial rights for two preclinical RNA interference (RNAi) subcutaneously delivered molecules for complement-mediated diseases, as well as an exclusive option for other preclinical RNAi molecules for two additional targets within the complement pathway. In addition to the collaboration agreement, we made an equity investment in Dicerna. Under the terms of the agreements, we made an upfront payment of $37.0 for the exclusive licenses and the equity investment. The market value of the equity investment was $10.3 as of the date of acquisition, which we recorded in other assets in our consolidated balance sheets. Due to the early stage of the assets we are licensing, we recorded the upfront license payment of $26.7 as research and development expense during the fourth quarter 2018. In December 2019, we exercised our option for exclusive rights to two additional targets within the complement pathway under an existing agreement with Dicerna, which expands Alexion’s existing research collaboration and license agreement with Dicerna to include a total of four targets within the complement pathway. In connection with the option exercise, we paid Dicerna $20.0, which we recorded as research and development expense in the fourth quarter 2019. As of December 31, 2019, we could be required to pay up to $629.1 for amounts due upon the achievement of specified research, development, regulatory and commercial milestones on the four licensed targets, as well as royalties on commercial sales. In December 2017, we entered into a collaboration and license agreement with Halozyme Therapeutics, Inc. that allows us to use drug-delivery technology in the development of subcutaneous formulations for our portfolio of products for up to four targets. Due to the early stage of the assets we are licensing, we recorded expense for the upfront payment of $40.0 during the fourth quarter 2017. In addition, as of December 31, 2019, we could be required to pay up to $160.0 for each target developed, subject to achievement of specified development, regulatory and sales-based milestones, as well as royalties on commercial sales. In connection with our prior acquisition of Syntimmune see Note 2, Acquisitions for additional information, we could be required to pay up to $800.0 upon the achievement of specified development, regulatory and commercial milestones. In addition, as of December 31, 2019, we have other license agreements under which we may be required to pay up to an additional $54.0 for currently licensed targets, if certain development, regulatory and commercial milestones are met. Additional amounts may be payable if we elect to acquire licenses to additional targets, as applicable, under the terms of these agreements. Asset Sale and Out-License Arrangements In connection with prior asset sale and out-license arrangements, Alexion is entitled to receive contingent payments upon the achievement of various regulatory and commercial milestones and other events, as well as royalties on commercial sales. The amount of contingent consideration related to these agreements is fully constrained and therefore has not been recognized as of December 31, 2019. Manufacturing Agreements We have various manufacturing development and license agreements to support our clinical and commercial product needs. We rely on Lonza, a third party manufacturer, to produce a portion of commercial and clinical quantities of our commercial products and product candidates. We have various manufacturing and license agreements with Lonza, with remaining total non-cancellable future commitments of approximately $1,099.9. This amount includes $100.0 of undiscounted, fixed payments applicable to our CMO embedded lease arrangement with Lonza. If we terminate certain supply agreements with Lonza without cause, we will be required to pay for product scheduled for manufacture under our arrangement. Under an existing arrangement with Lonza, we also pay Lonza a royalty on sales of SOLIRIS that was manufactured at the Alexion Rhode Island Manufacturing Facility (ARIMF facility) prior to the sale of the facility and a payment with respect to sales of SOLIRIS manufactured at Lonza facilities. We also pay Lonza a royalty on the sales of ULTOMIRIS. In addition to our commitments with Lonza, as of December 31, 2019, we have non-cancellable commitments of approximately $60.6 through 2020 with other third party manufacturers. Contingent Liabilities We are currently involved in various claims, disputes, lawsuits, investigations, administrative proceedings and legal proceedings. On a quarterly basis, we review the status of each significant matter and assess its potential financial exposure. In accordance with generally accepted accounting principles, if the potential loss from any claim, asserted or unasserted, or legal proceeding is considered probable and the amount can be reasonably estimated, we accrue a liability for the estimated loss. Because of uncertainties related to claims, proceedings and litigation, accruals are based on our best estimates based on information available at the time of the assessment. On a periodic basis, as additional information becomes available, or based on specific events such as the outcome of litigation, court decisions or settlement of claims (and offers of settlement), we may reassess the potential liability related to these matters and may revise these estimates, which could result in a material adverse adjustment to our operating results. Costs associated with our involvement in legal proceedings are expensed as incurred. The outcome of any such proceedings, regardless of the merits, is inherently uncertain. If we were unable to prevail in any such proceedings, our consolidated financial position, results of operations, and future cash flows may be materially impacted. We have received, and may in the future receive, notices from third parties claiming that their patents may be infringed by the use, development, manufacture, importation or sale of our products or product candidates. Under the guidance of ASC 450, Contingencies, we record a royalty accrual based on our best estimate of the fair value percent of net sales of our products that we could be required to pay the owners of patents for technology used in the manufacture and sale of our products. A costly license, or inability to obtain a necessary license, could have a material adverse effect on our financial results. In May 2015, we received a subpoena in connection with an investigation by the Enforcement Division of the Securities and Exchange Commission (SEC) requesting information related to our grant-making activities and compliance with the Foreign Corrupt Practices Act (FCPA) in various countries. In addition, in October 2015, we received a request from the Department of Justice (DOJ) for the voluntary production of documents and other information pertaining to Alexion’s compliance with FCPA. The SEC and DOJ also seek information related to Alexion’s recalls of specific lots of SOLIRIS and related securities disclosures. Alexion is cooperating with these investigations. The investigations have focused on operations in various countries, including Brazil, Colombia, Japan, Russia and Turkey, and Alexion's compliance with the FCPA and other applicable laws. Preliminary discussions have begun with the SEC to resolve the investigation. However, at this time, Alexion is unable to predict the duration, scope or outcome of these preliminary discussions with the SEC or the investigations at the SEC or DOJ. There can be no assurance that any current or future discussions with the SEC or DOJ to resolve these matters will be successful or that any potential settlement terms or amount will be agreed to or finalized. While it is possible that a loss related to these matters may be incurred, given the ongoing nature of the discussions with the SEC and these investigations at the SEC and DOJ, management cannot reasonably estimate the potential magnitude of any such loss or range of loss, or the cost of the ongoing investigation. Any determination that our operations or activities are not or were not in compliance with existing laws or regulations could result in the imposition of fines, civil and criminal penalties, equitable remedies, including disgorgement, injunctive relief, and/or other sanctions against us, and remediation of any such findings could have an adverse effect on our business operations. Alexion is committed to strengthening its compliance program and is currently enhancing and continuing to implement a comprehensive company-wide transformation plan that is designed to enhance our business processes, structures, controls, training, talent and systems across Alexion’s global operations. As previously reported, on December 29, 2016, a shareholder filed a putative class action against the Company and certain former employees in the U.S. District Court for the District of Connecticut, alleging that defendants made misrepresentations and omissions about SOLIRIS. On April 12, 2017, the court appointed a lead plaintiff. On July 14, 2017, the lead plaintiff filed an amended putative class action complaint against the Company and seven current or former employees. Defendants moved to dismiss the amended complaint on September 12, 2017. Plaintiffs filed an opposition to defendants’ motion to dismiss on November 13, 2017, and defendants filed a reply brief in further support of their motion on December 28, 2017. On March 26, 2019, the court held a telephonic status conference. During that conference, the court informed counsel that it was preparing a ruling granting the defendants’ pending motion to dismiss. The court inquired of plaintiffs’ counsel whether they intended to seek leave to amend their complaint, and indicated that if they wished to file a second amended complaint, they would be allowed to do so. On April 2, 2019, the court granted plaintiffs until May 31, 2019 to file a second amended complaint, thereby rendering moot defendants’ pending motion to dismiss. On May 31, 2019, plaintiffs filed a second amended complaint against the same defendants. The complaint alleges that defendants engaged in securities fraud, including by making misrepresentations and omissions in its public disclosures concerning the Company’s SOLIRIS sales practices, management changes, and related investigations, between January 30, 2014 and May 26, 2017, and that the Company's stock price dropped upon the purported disclosure of the alleged fraud. The plaintiffs seek to recover unspecified monetary relief, unspecified equitable and injunctive relief, interest, and attorneys’ fees and costs. Defendants’ filed a motion to dismiss the amended complaint on August 2, 2019; plaintiffs’ filed their opposition to that motion on October 2, 2019; and defendants’ filed their reply in further support of their motion on November 16, 2019. Given the early stage of these proceedings, we cannot presently predict the likelihood of obtaining dismissal of the case (or the ultimate outcome of the case if the motion to dismiss is denied by the court), nor can we estimate the possible loss or range of loss at this time. In December 2016, we received a subpoena from the U.S. Attorney's Office for the District of Massachusetts requesting documents relating generally to our support of Patient Services, Inc. (PSI) and National Organization for Rare Disorders (NORD), 501(c)(3) organizations that provide financial assistance to Medicare patients taking drugs sold by Alexion; Alexion’s provision of free drug to Medicare patients; and Alexion compliance policies and training materials concerning the anti-kickback statute and information on donations to PSI and NORD from 2010 through 2016. In April 2019, we entered into a civil settlement agreement with the DOJ and the Office of Inspector General (OIG) of the U.S. Department of Health and Human Services to resolve this matter. As part of the settlement agreement, Alexion paid $13.1 to the DOJ and OIG. OIG did not require a Corporate Integrity Agreement with Alexion because it made fundamental organizational changes, including hiring a new executive leadership team, replacing half of the members of its Board of Directors, and effecting a significant change in the workforce. In May 2017, Brazilian authorities seized records and data from our Sao Paulo, Brazil offices as part of an investigation being conducted into Alexion’s Brazilian operations. We are cooperating with this inquiry. In June 2017, we received a demand to inspect certain of our books and records pursuant to Section 220 of the General Corporation Law of the State of Delaware on behalf of a purported stockholder. Among other things, the demand sought to determine whether to institute a derivative lawsuit against certain of the Company’s directors and officers in relation to the investigation by our Audit and Finance Committee announced in November 2016 and the investigations instituted by the SEC, DOJ, U.S. Attorney’s Office for the District of Massachusetts, and Brazilian law enforcement officials that are described above. We have responded to the demand. Given the early stages of this matter, an estimate of the possible loss or range of loss cannot be made at this time. On September 27, 2017, a hearing panel of the Canadian Patented Medicine Prices Review Board (PMPRB) issued a decision in a previously pending administrative pricing matter that we had excessively priced SOLIRIS in a manner inconsistent with the Canadian pricing rules and guidelines. In its decision, the PMPRB ordered Alexion to decrease the price of SOLIRIS to an upper limit based upon pricing in certain other countries, and to forfeit excess revenues for the period between 2009 and 2017. The amount of excess revenues for the period between 2009 and 2017 was not determined to be a material amount and was paid in 2018. In October 2017, Alexion filed an application for judicial review of the PMPRB’s decision in the Federal Court of Canada. On May 23, 2019, the Federal Court of Canada dismissed Alexion's application for judicial review and, as a consequence, affirmed the decision of the PMPRB that we had excessively priced SOLIRIS. On June 21, 2019, Alexion filed a notice of appeal of the Federal Court of Canada's ruling and on October 17, 2019, Alexion filed a memorandum of fact and law in support of the appeal. On December 3, 2019, the Attorney General of Canada filed its memorandum of fact and law in support of the Federal Court of Canada’s dismissal of Alexion’s appeal of the PMPRB’s decision. On December 19, 2019, intervenor, the Minister of Health for the Province of British Columbia, filed a separate memorandum of fact and law in support of the Federal Court of Canada’s decision. Pursuant to an order made by the Federal Court of Canada, as of February 4, 2020, we have placed approximately $43.4 in escrow to secure our obligations pending the final resolution of all appeals in this matter. This amount reflects the difference between the list price for SOLIRIS and the price determined by the PMPRB to be non-excessive for sales of SOLIRIS in Canada for the period beginning September 2017 through December 31, 2019. In addition, on a quarterly basis until the appeals process has concluded, Alexion will be required to place amounts into escrow for each vial of SOLIRIS sold in the applicable quarter equal to the list price for SOLIRIS and the price determined by the PMPRB to be non-excessive. Our revenues in Canada recognized in the year ended December 31, 2019 were reduced by $29.8, which is our current best estimate of our liability through December 31, 2019 if we lose the appeal of this matter (the amount of our ultimate liability, however, may be greater than this estimate when the appeal process for this matter is concluded). Chugai Pharmaceutical Co., Ltd. has filed three lawsuits against Alexion. The first was filed in November 2018 in the United States District Court for the District of Delaware against Alexion Pharmaceuticals, Inc. alleging that ULTOMIRIS infringes one U.S. patent held by Chugai Pharmaceutical Co., Ltd. Upon issuance of a new U.S. patent on November 12, 2019, Chugai filed a second lawsuit in the United States alleging ULTOMIRIS infringes the new patent. The parties have agreed to consolidate the November 2018 and November 2019 lawsuits. Chugai filed a lawsuit in December 2018 in the Tokyo District Court against Alexion Pharma GK (a wholly-owned subsidiary of Alexion) in Japan and alleges that ULTOMIRIS infringes two Japanese patents held by Chugai Pharmaceutical Co., Ltd. Chugai’s complaints seek unspecified damages and certain injunctive relief. In all cases, Alexion has denied the charges and countered that the patents are neither valid nor infringed. A trial date for the U.S. case has been set for June 2021. The case is still at the briefing stage in Japan. Given the early stages of these litigations, an estimate of the possible loss or range of loss cannot be made at this time. On February 28, 2019, Amgen Inc. (Amgen) petitioned the U.S. Patent and Trademark Office (PTO) to institute Inter Partes Review (IPR) of three patents owned by Alexion that relate to SOLIRIS: U.S. Patent Nos. 9,725,504; 9,718,880; and 9,732,149. In each case, Amgen alleges the patented subject matter was anticipated and/or obvious in view of prior art, and that the patent claims are therefore invalid. On August 30, 2019, the PTO instituted IPRs of each of the three patents. We expect the PTO to review written submissions by both parties, hold an oral argument, and issue decisions on the three IPRs by August 30, 2020. At this time we cannot determine what decision the PTO will make. In connection with an ongoing matter, in August 2019, the Brazilian Federal Revenue Service provided a Notice of Tax and Description of the Facts (the “Tax Assessment”) to two Alexion subsidiaries (the "Brazil Subsidiaries"), as well as to two additional entities, a logistics provider utilized by Alexion and a distributor. The Tax Assessment focuses on the importation of SOLIRIS vials pursuant to Alexion’s free drug supply to patients program (referred to as Global Access to Medicines, or GATM) in Brazil. In September 2019, the Brazil Subsidiaries filed defenses to the Tax Assessment disputing the basis for liability under the Tax Assessment based on, among others, the following: in connection with the operation of GATM, during the period from September 2014 to June 2019: (i) the importers responsible for the importation of the GATM SOLIRIS vials into Brazil were correctly identified and (ii) the correct customs value was utilized for the purpose of importing the GATM SOLIRIS vials provided to the patients free of charge. There are three separate levels of administrative appeals within the Brazilian federal administrative proceeding system and, if the outcome of these administrative appeals is unfavorable, the final decision of the federal administrative proceeding system can be disputed to the federal court systems in Brazil (at this time, Alexion intends to appeal the Tax Assessment if it is not overturned in the course of administrative appeals). Given the early stage of these proceedings, Alexion is unable to predict the duration, scope or outcome of this matter, but we expect that a final resolution will take three years or more. While it is possible that a loss related to the Tax Assessment may be incurred, given its ongoing nature, we cannot reasonably estimate the potential magnitude of any such possible loss or range of loss, or the cost of the ongoing administrative appeals (and potential appeals to the federal court system) of the Tax Assessment. Any determination that any aspects of the importation of free of charge medications into Brazil as set forth in the Tax Assessment are not or were not in compliance with existing laws or regulations could result in the imposition of fines, civil penalties and, potentially criminal penalties, and/or other sanctions against us and could have an adverse impact on our Brazilian operations.

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

Income tax expense is based on income before income taxes as follows:



	Year Ended December 31,
	2019		2018			2017
U.S.	$	2.0	$	(451.4	)	$	(43.9	)
Non-U.S.	2,176.8		693.6			591.7
	$	2,178.8	$	242.2		$	547.8

During the fourth quarter of 2013, in connection with the centralization of our global supply chain and technical operations in Ireland, our U.S. parent company became a direct partner in a captive foreign partnership. The partnership income, which is derived in foreign jurisdictions, is classified as “non-U.S. income” for purposes of financial reporting. Substantially all non-U.S. income relates to income from our captive foreign partnership.

The components of income tax expense are as follows:



	Year Ended December 31,
	2019			2018			2017
Domestic
Current	$	71.8		$	57.0		$	42.9
Deferred	1,731.0			49.5			7.2
	1,802.8			106.5			50.1
Foreign
Current	158.2			74.7			107.5
Deferred	(2,186.5		)	(16.6		)	(53.1		)
	(2,028.3		)	58.1			54.4
Total
Current	230.0			131.7			150.4
Deferred	(455.5		)	32.9			(45.9		)
	$	(225.5	)	$	164.6		$	104.5

We continue to pay cash taxes in U.S. federal, various U.S. state, and foreign jurisdictions where we have utilized all of our tax attributes or have met the applicable limitation for attribute utilization.

Effective Tax Rate

The provision (benefit) for income taxes differs from the U.S. federal statutory tax rate. The reconciliation of the statutory U.S. federal income tax rate to our effective income tax rate is as follows:



	Year Ended December 31,
	2019		2018		2017
U.S. federal statutory tax rate	21.0	%	21.0	%	35.0	%
Benefit of foreign earnings	(12.6	)%	(71.2	)%	60.1	%
Tax credits	(0.7	)%	(17.0	)%	(10.7	)%
Tax reserves	(0.1	)%	12.1	%	(14.0	)%
Re-measurement of deferred taxes as a result of the Tax Act	—	%	—	%	(53.4	)%
Acquired in-process research & development	—	%	102.6	%	—	%
Intra-entity asset transfer of intellectual property	(17.5	)%	—	%	—	%
Foreign-derived intangible income	(1.6	)%	(4.5	)%	—	%
U.S. state taxes	0.7	%	14.2	%	1.5	%
Other permanent differences	0.5	%	10.8	%	0.6	%

Effective Income Tax Rate	(10.3	)%	68.0	%	19.1	%

In our reconciliation of our statutory U.S. federal income tax rate to our effective tax rate above, we have included a benefit of foreign earnings amount which encapsulates the various tax impacts that result from our non-U.S. income. As a result of U.S. Tax Reform, a substantial portion of our foreign earnings are subject to the GILTI minimum tax at an effective rate which is lower than the U.S. statutory tax rate of 21.0%. While we are also subject to tax in foreign jurisdictions locally, substantially all of these current taxes are creditable against U.S. taxes imposed on foreign earnings. As a result, the effective tax rate on our foreign earnings is lower than the U.S. statutory rate.

In the year ended December 31, 2019, the benefit of foreign earnings includes foreign local tax expense of $193.2, which is offset by the benefit from U.S. foreign tax credits of $196.1, resulting in a net decrease to the effective tax rate of 0.1%. We incurred U.S. tax expense on our foreign earnings of $187.6, which includes GILTI minimum tax. The U.S. tax on our foreign earnings reflects a benefit of $269.5, or 12.4%, primarily related to the Section 250(a) deduction, compared to the statutory rate. The benefit from foreign earnings also includes certain one-time tax benefits associated with the intellectual property of Wilson Therapeutics. The deferred tax benefits include $95.7and $30.3 associated

with a tax election made with respect to intellectual property of Wilson Therapeutics and a valuation allowance release and corresponding recognition of net operating losses, respectively. On July 1, 2019, the Wilson Therapeutics intellectual property was integrated into the Alexion corporate structure, resulting in income tax expense of approximately $10.2.

In the year ended December 31, 2019, the Company completed an intra-entity asset transfer of certain intellectual property to an Irish subsidiary within our captive foreign partnership. The Company recognized deferred tax benefits of $2,221.5 which represents the difference between the basis of the intellectual property for financial statement purposes and the basis of the intellectual property for tax purposes, applying the appropriate enacted statutory tax rates. The Company will receive future tax deductions associated with amortization of the intellectual property, and any amortization not deducted for tax purposes will be carried forward indefinitely under Irish tax law. An offsetting deferred tax expense of $1,839.3 has been recognized to reflect the reduction of future foreign tax credits associated with the foreign local tax amortization deductions. These net deferred tax benefits resulted in a decrease of approximately 17.5% to our effective tax rate.

We also completed a comprehensive analysis of our prior year estimate related to our foreign-derived intangible income (“FDII”) based on additional guidance provided in the proposed regulations issued by the U.S. Treasury Department in 2019. The analysis resulted in income tax benefit of $17.0 related to prior year, which was recorded as a change in estimate in income tax expense in our consolidated statements of operations, resulting in a decrease of approximately 0.8% to our effective tax rate.

In the year ended December 31, 2018, the benefit of foreign earnings includes foreign local tax expense of $58.1, substantially all of which is offset by the benefit from U.S. foreign tax credits of $54.2, resulting in a net increase to the effective tax rate of 1.6%. We incurred U.S. tax expense on our foreign earnings of $206.1, which includes GILTI minimum tax. The U.S. tax on our foreign earnings reflects a benefit of $108.7, or 44.8%, primarily related to the Section 250(a) deduction, compared to the U.S. statutory rate. Also included in this component is a benefit of $67.7 from adjustments to 2018 provisional accounting for the Tax Act, which resulted in a decrease to our effective tax rate of approximately 28.0%.

In the year ended December 31, 2017, the benefit of foreign earnings includes foreign local tax expense of $54.4 partially offset by the benefit from U.S. foreign tax credits of $33.2, resulting in a net increase to the effective tax rate of 3.9%. We incurred transition tax imposed by the Tax Act of $177.9 and US deferred taxes related to the GILTI provisions of the Tax Act of $165.4. These Tax Act-related adjustments resulted in an increase to our effective tax rate of approximately 62.7%. Additional U.S. tax imposed on our foreign earnings of $171.7 reflects a benefit of $35.4 or 6.5% compared to the U.S. statutory rate.

The effective tax rate reconciliation includes the tax impact of acquisitions of IPR&D assets. Absent successful clinical results and regulatory approval, there is no alternative use for certain acquired IPR&D assets. An increase to the effective tax rate results when the value of such assets are expensed, and no tax benefit is recognized. In the year ended December 31, 2018, this component of the effective tax rate includes an increase to tax expense of $248.4 related to the acquired IPR&D costs for the acquisitions of Wilson Therapeutics and Syntimmune, which increased our effective tax rate by 69.7% and 32.9%, respectively.

In the year ended December 31, 2018, other permanent differences includes tax expense of $21.1 or 8.7% related to nondeductible compensation.

In 2017, we concluded the IRS examination of our 2013 and 2014 tax years. Conclusion of the IRS examination resulted in a decrease to the tax reserves component of the 2017 effective tax rate of approximately 3.6%.

The Tax Act

In December 2017, the Tax Cuts and Jobs Act (Tax Act) was enacted into law. The Tax Act decreased the US federal corporate tax rate to 21.0%, imposed a minimum tax on foreign earnings related to intangible assets (GILTI), a one-time transition tax on previously unremitted foreign earnings, and modified the taxation of other income and expense items. With regard to the GILTI minimum tax, foreign earnings are reduced by the profit attributable to tangible assets and a deductible allowance of up to 50.0%, subject to annual limitations. We have elected to account for the impact of the minimum tax in deferred taxes.

At December 31, 2017, the Tax Act resulted in an increase to tax expense and the effective tax rate of $45.8 and 8.4%, respectively:


(a)	Income tax expense increased $177.9 or 32.5% related to the transition tax on unremitted earnings imposed by the Tax Act. This increase includes foreign income subject to US tax of $195.6, partially offset by a related benefit of foreign tax credits of $17.7.


(b)	The decrease to the U.S. federal tax rate resulted in a decrease to deferred tax expense of $292.4 or 53.4%. This decrease includes the $121.3 or 22.2% benefit of re-measuring domestic deferred taxes and an additional decrease attributable to re-measuring deferred taxes on foreign earnings of $171.1 or 31.2%.


(c)	Other permanent differences includes a decrease to tax expense of $5.1 or 0.9% related to the re-measurement of income taxes payable as a result of changes in U.S. federal tax rates under the Tax Act.


(d)	The enactment of the GILTI minimum tax increased US deferred taxes on foreign earnings $165.4 or 30.2%. This increase includes deferred tax expense related to the GILTI minimum tax of $236.9. This deferred expense is partially offset by a related decrease to deferred expense for the release of reserves for uncertain tax positions of $71.5.

We calculated provisional amounts for the tax effects of the Tax Act that could be reasonably estimated, but not completed, in our results for the year ended December 31, 2017. As of the fourth quarter 2018 we had completed our analysis of all provisional estimates, and concluded as follows:

(a)

We calculated a reasonable estimate of the one-time transition tax on previously unremitted earnings, which resulted in an increase to U.S. Federal tax expense of $177.9 and an increase to taxes payable, net of tax credits, of $28.0 in the period ended December 31, 2017. Our initial accounting for the transition tax was not complete as of December 31, 2017 because there was uncertainty regarding the calculation of the amounts subject to the tax. We completed our analysis of the transition tax and related interpretive guidance during the third quarter 2018. No significant measurement period adjustment to our initial accounting was required.

(b)

We calculated a reasonable estimate of the impact of the GILTI minimum tax on deferred taxes, which resulted in an increase to U.S. Federal tax expense and the deferred tax liability of $236.9 in the period ended December 31, 2017. Our initial accounting for the minimum tax was incomplete because there was uncertainty regarding the calculation of the temporary differences subject to the minimum tax. We completed our analyses of these temporary differences and the expected timing and manner of their reversal during the fourth quarter 2018. We recorded measurement period adjustments during 2018 which resulted in a decrease to U.S. federal tax expense of $67.7.

(c)

We calculated a reasonable estimate of the Tax Act’s limits on deductions for employee remuneration, including remuneration in kind, which resulted in an insignificant impact to tax expense, taxes payable, and deferred taxes in the period ended December 31, 2017. Our initial accounting for these limits was incomplete because there was uncertainty regarding the value of the deduction-limited remuneration. We completed our analysis of the relevant employee remuneration arrangements during the third quarter 2018. No measurement period adjustment to our initial accounting was required.

(d)

We calculated a reasonable estimate of the impact of the Tax Act to U.S. state income taxes, which resulted in an increase to tax expense, taxes payable, and deferred taxes of $2.9, $2.2, and $0.7, respectively, in the period ended December 31, 2017. We interpreted the effect of the Tax Act's changes to federal law on each U.S. state's system of taxation as of the date of enactment. We completed additional analysis of the effect of modifications to federal deductions and income inclusions on U.S. state tax systems in the fourth quarter 2018. No measurement period adjustment to our initial accounting was required.

(e)

We calculated the deferred tax liability related to our foreign captive partnership in the period ended December 31, 2017 consistent with our calculation in periods prior to enactment of the Tax Act. As a result, the deferred tax liability we recorded as of December 31, 2017 of $533.4 related to our foreign captive partnership was provisional. We completed additional analysis of the direct and indirect effects of the Tax Act during the fourth quarter 2018. We recorded measurement period adjustments during 2018 which resulted in an increase to U.S. state income tax expense and deferred taxes of $11.1.

Deferred Taxes

Provisions have been made for deferred taxes based on the differences between the basis of the assets and liabilities for financial statement purposes and the basis of the assets and liabilities for tax purposes using currently

enacted tax rates and regulations that will be in effect when the differences are expected to be recovered or settled. The components of the deferred tax assets and liabilities are as follows:



	December 31,			December 31,
	2019			2018
Deferred tax assets:
Net operating losses	$	102.9		$	41.8
Income tax credits	328.1			371.6
Stock compensation	57.1			47.6
Accruals and allowances	65.2			105.8
Unrealized losses	18.8			—
Research and development expenses	3.5			5.2
Accrued royalties	0.8			89.1
ROU leases	46.2			—
Intangible assets	1,967.3			—
	2,589.9			661.1
Valuation allowance	(72.6		)	(19.6		)
Total deferred tax assets	2,517.3			641.5
Deferred tax liabilities:
Depreciable assets	(5.1		)	(88.7		)
Unrealized gains	—			(6.6		)
Investment in foreign partnership	(2,249.5		)	(566.6		)
ROU leases	(53.9		)	—
Intangible liabilities	—			(268.8		)
Total deferred tax liabilities	(2,308.5		)	(930.7		)
Net deferred tax (liability) asset	$	208.8		$	(289.2	)

At December 31, 2019, we have tax effected federal and state net operating loss carryforwards of $12.5 and $43.7, respectively. Our net operating losses expire between 2022 and 2040. We also have federal and state income tax credit carryforwards of $280.5 and $67.3 respectively. The federal income tax credits expire between 2033 and 2039, whereas $47.2 of state income tax credit carryforwards expire between 2020 and 2034. The remaining $20.1 of state income tax credits can be carried forward indefinitely.

Included in the year ended December 31, 2019 are $27.3 of Connecticut state net operating loss carryforwards and $39.7 of Connecticut state income tax credit carryforwards. A change in the Connecticut state tax regime signed into law during 2019 phases out the capital-based component of the business tax. Once fully phased out, the Company will be subject to income-based taxes in the state of Connecticut. The Company anticipates generating tax credits in future years that exceed the amount that can otherwise be utilized. As a result, a full valuation allowance has been established against these carryforward attributes.

The increase in our net operating losses primarily relates to our technical operations center in Ireland, which received a tax benefit during the year for previously accrued but unpaid royalties. The decrease in income tax credits is attributable to the utilization of Orphan Drug credits, partially offset by an increase to fully valued Connecticut state tax credits due to the change in the state tax regime. We continue to maintain a valuation allowance against other certain deferred tax assets where realization is not certain.

The increase in our intangible deferred tax assets relates to the intra-entity asset transfer of certain intellectual property to an Irish subsidiary within our captive foreign partnership. The recognized deferred tax benefit represents the difference between the basis of the intellectual property for financial statement purposes and the basis of the intellectual property for tax purposes. This transaction also increased our investment in foreign partnership deferred tax liability due to the recognition of anticipatory foreign tax credits that reflect the reduction of future foreign taxes associated with the foreign local tax amortization deductions.

Included in our investment in foreign partnership above is $(1,408.2) associated with GILTI minimum tax.

Unrecognized Tax Benefits

We follow authoritative guidance regarding accounting for uncertainty in income taxes, which prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The interpretation also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosures, and transition.

The beginning and ending amounts of unrecognized tax benefits reconciles as follows:



	2019			2018			2017
Beginning of period balance	$	92.7		$	60.9		$	138.9
Increases for tax positions taken during a prior period	3.4			9.1			5.6
Decreases for tax positions taken during a prior period	(4.9		)	(5.8		)	(85.8		)
Increases for tax positions taken during the current period	43.8			28.8			19.3
Decreases for tax positions related to settlements	—			—			(15.8		)
Decreases for tax positions related to lapse of statute	(1.2		)	(0.3		)	(1.3		)
	$	133.8		$	92.7		$	60.9

The total amount of accrued interest and penalties were not significant as of December 31, 2019. The total amount of tax benefit recorded during 2019, 2018, and 2017 which related to unrecognized tax benefits was $4.6, $35.4, and $27.1, respectively. All of our unrecognized tax benefits, if recognized, would have a favorable impact on the effective tax rate.

It is reasonably possible that a portion of our unrecognized tax benefits could reverse within the next twelve months. Reversal of these amounts is contingent upon the completion of field audits by the taxing authorities in several jurisdictions, whether a tax adjustment is proposed, the nature and amount of any adjustment, and the administrative path to resolving the proposed adjustment. We cannot reasonably estimate the range of the potential change.

Tax Audits

We file federal and state income tax returns in the U.S. and in numerous foreign jurisdictions. The U.S. and foreign jurisdictions have statutes of limitations ranging from 3 to 6 years. However, the limitation period could be extended due to our tax attribute carryforward position in a number of our jurisdictions. The tax authorities generally have the ability to review income tax returns for periods where the limitation period has previously expired and can subsequently adjust tax attribute values.

In 2017, the IRS commenced an examination of our U.S. income tax returns for 2015. We anticipate this audit will conclude within the next twelve months. We have not been notified of any significant adjustments proposed by the IRS. It is reasonably possible that previously unrecognized tax benefits could be recognized upon the conclusion of the IRS examination. At this time, an estimate of the change in unrecognized tax benefits cannot be made.

Undistributed Earnings

We have recorded tax on the undistributed earnings of our controlled foreign corporation (CFC) subsidiaries. To the extent CFC earnings may not be repatriated to the U.S. as a dividend distribution due to limitations imposed by law, we have not recorded the related potential withholding, foreign local, and U.S. state income taxes.

Share-based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-based Compensation

2017 Incentive Plan

The 2017 Plan was approved by our stockholders in May 2017 and replaced the 2004 Plan effective May 10, 2017. The 2017 Plan is a broad based plan that provides for the grant of equity awards including restricted stock and restricted stock units (collectively referred to as Restricted Stock), incentive and non-qualified stock options, and other stock-related awards to our directors, officers, key employees and consultants, for up to a maximum of 18.2 shares in addition to awards outstanding under the 2004 Incentive Plan on or after March 14, 2017 that are subsequently canceled, cash settled, expired, forfeited, or otherwise terminated without the delivery of such shares, subject to the limitations in the 2017 Plan. Stock options granted under the 2017 Plan have a maximum contractual term of ten years from the date of grant, have an exercise price not less than the fair value of the stock on the grant date and generally vest over four years. Restricted Stock awards also generally vest over four years, with performance-based restricted stock units having a three-year vesting period.

Stock Options

A summary of the status of our stock options at December 31, 2019, and changes during the year then ended is presented in the table and narrative below:



	Number of shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2018	3.6		$	119.68
Granted	—		—
Exercised	(0.3	)	67.87
Forfeited and canceled	(0.3	)	158.71
Outstanding at December 31, 2019	3.0		$	119.51	4.08	$	49.0
Vested and unvested expected to vest at December 31, 2019	3.0		$	119.49	4.07	$	49.0
Exercisable at December 31, 2019	2.9		$	119.15	3.93	$	48.9

Total intrinsic value of stock options exercised during the years ended December 31, 2019, 2018 and 2017 was $14.7, $27.5 and $88.9, respectively. We primarily utilize newly issued shares to satisfy the exercise of stock options. The total fair value of options vested during the years ended December 31, 2019, 2018 and 2017 was $10.1, $27.2 and $61.5, respectively.

We did not grant any stock options during the years ended December 31, 2019 and 2018. For the year ended December 31, 2017, the fair value of options at the date of grant was estimated using the Black-Scholes model with the following ranges of weighted average assumptions:



	December 31,
	2017
Expected life in years	4.07 - 4.29
Interest rate	1.64% - 1.92%
Volatility	38.78% - 39.01%
Dividend yield	—

The expected stock price volatility rates are based on historical volatilities of our common stock. The risk-free interest rates are based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. The average expected life represents the weighted average period of time that options granted are expected to be outstanding. We have evaluated three distinct employee groups in determining the expected life assumptions, and we estimate the expected life of stock options based on historical experience of exercises, cancellations and forfeitures of our stock options.

The weighted average fair value at the date of grant for options granted during the year ended December 31, 2017 was $42.59.

Restricted Stock

A summary of the status of our nonvested Restricted Stock at December 31, 2019 and changes during the year then ended is as follows:



	Number of Shares	Weighted Average Grant Date Fair Value
Nonvested Restricted Stock at December 31, 2018	3.7	$	123.25
Shares granted	2.4	133.89
Shares forfeited	0.5	126.76
Shares vested	1.3	125.02
Nonvested Restricted Stock at December 31, 2019	4.3	$	128.24

The fair value of Restricted Stock at the date of grant is based on the fair market value of the shares of common stock underlying the awards on the date of grant. The weighted average fair value at the date of grant for Restricted Stock awards granted during the years ended December 31, 2019, 2018 and 2017, including restricted stock units with performance conditions, was $133.89, $119.27 and $125.39 per share, respectively. The total fair value of Restricted Stock vested during the years ended December 31, 2019, 2018 and 2017 was $161.3, $181.7 and $157.0, respectively.

Included in the table above is 0.4 shares granted to senior management that include both market-based and non-market-based performance conditions which provide the recipient the right to receive restricted stock at the end of a three year performance period. We used payout simulation models to estimate the grant date fair value of these awards at $147.79. Expense recognized for these awards was $46.3 and $14.9 for the years ended December 31, 2019 and 2018 and immaterial for the year ended December 31, 2017.

Employee Stock Purchase Plan

During 2015, the Company adopted the ESPP under which employees can purchase shares of our common stock based on a percentage of their compensation subject to certain limits. The purchase price per share is equal to the lower of 85.0% of the fair market value of our common stock on the offering date or the purchase date with a six month look-back feature. Under the ESPP, up to 1.0 shares of common stock may be issued to eligible employees who elect to participate in the purchase plan. Shares issued and compensation expense recognized under the ESPP for the years ended December 31, 2019, 2018 and 2017 were not material.

Share-Based Compensation Expense

The following table summarizes the share-based compensation expense in the consolidated statements of operations:



	Year Ended December 31,
	2019			2018			2017
Cost of sales	$	14.1		$	16.0		$	11.1
Research and development	61.8			57.5			76.4
Selling, general and administrative	161.1			129.5			155.6
Total share-based compensation expense	237.0			203.0			243.1
Income tax effect	(55.0		)	(46.5		)	(89.3		)
Total share-based compensation expense, net of tax	$	182.0		$	156.5		$	153.8

Share-based compensation expense capitalized to inventory during the years ended December 31, 2019, 2018 and 2017 was $12.9, $14.5, and $15.4, respectively.

As of December 31, 2019, there was $351.4 of total unrecognized share-based compensation expense related to non-vested share-based compensation arrangements granted under our share-based compensation plans. The expense is expected to be recognized over a weighted-average period of 1.71 years.

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2019
Common and Preferred Stock [Abstract]
Stockholders' Equity	Stockholders’ Equity Share Repurchases In November 2012, our Board of Directors authorized a share repurchase program. In February 2017, our Board of Directors increased the amount that we are authorized to expend on future repurchases to $1,000 under the repurchase program, which superseded all prior repurchase programs. On October 22, 2019, the Board of Directors approved an additional share repurchase authorization of up to $1,000. The repurchase program does not have an expiration date and we are not obligated to acquire a particular number of shares. The repurchase program may be discontinued at any time at our discretion. Under the program, we repurchased 3.8 and 0.7 shares of our common stock at a cost of $416.0 and $85.0 during the years ended December 31, 2019 and 2018, respectively. Subsequent to December 31, 2019, we repurchased an immaterial number of shares of common stock under our repurchase program at a cost of $1.6. As of February 4, 2020, there is a total of $1,033.9 remaining for repurchases under the repurchase program.

Other Comprehensive Income and Accumulated Other Comprehensive Income (Notes)

12 Months Ended

Dec. 31, 2019

Other Comprehensive Income and Accumulated Other Comprehensive Income [Abstract]

Other Comprehensive Income and Accumulated Other Comprehensive Income

The following table summarizes the changes in AOCI, by component, for the years ended December 31, 2019, 2018 and 2017:



	Defined Benefit Pension Plans			Unrealized Gains (Losses) from Debt Securities			Unrealized Gains (Losses) from Hedging Activities			Foreign Currency Translation Adjustment			Total Accumulated Other Comprehensive Income (Loss)
Balances, December 31, 2016	$	(6.7	)	$	(0.4	)	$	91.9		$	(24.3	)	$	60.5
Other comprehensive income (loss) before reclassifications	0.5			(0.2		)	(88.2		)	8.4			(79.5		)
Amounts reclassified from other comprehensive income	1.4			0.8			(17.6		)	—			(15.4		)
Net other comprehensive income (loss)	1.9			0.6			(105.8		)	8.4			(94.9		)
Balances, December 31, 2017	$	(4.8	)	$	0.2		$	(13.9	)	$	(15.9	)	$	(34.4	)
Other comprehensive income (loss) before reclassifications	1.5			0.1			32.9			(0.5		)	34.0
Amounts reclassified from other comprehensive income	0.7			(0.6		)	(9.4		)	—			(9.3		)
Net other comprehensive income (loss)	2.2			(0.5		)	23.5			(0.5		)	24.7
Balances, December 31, 2018	$	(2.6	)	$	(0.3	)	$	9.6		$	(16.4	)	$	(9.7	)
Other comprehensive income (loss) before reclassifications	(6.6		)	0.2			(11.1		)	(1.0		)	(18.5		)
Amounts reclassified from other comprehensive income	—			—			(38.6		)	—			(38.6		)
Net other comprehensive income (loss)	(6.6		)	0.2			(49.7		)	(1.0		)	(57.1		)
Balances, December 31, 2019	$	(9.2	)	$	(0.1	)	$	(40.1	)	$	(17.4	)	$	(66.8	)

The table below provides details regarding significant reclassifications from AOCI during the years ended December 31, 2019, 2018 and 2017:



Details about Accumulated Other Comprehensive Income Components	Amount Reclassified From Accumulated Other Comprehensive Income during the year ended December 31,									Affected Line Item in the Consolidated Statements of Operations
	2019			2018			2017
Unrealized Gains (Losses) on Hedging Activity
Forward exchange forward contracts	$	36.8		$	(1.8	)	$	28.9		Net product sales
Interest rate swap contracts	13.3			13.6			(1.8		)	Interest expense
	50.1			11.8			27.1
	(11.5		)	(2.4		)	(9.5		)	Income tax (benefit) expense
	$	38.6		$	9.4		$	17.6
Defined Benefit Pension Items
Amortization of prior service costs and actuarial losses	$	—		$	(0.3	)	$	(0.4	)	^(a)
Curtailment	—			(0.6		)	(1.8		)	^(a)
	—			(0.9		)	(2.2		)
	—			0.2			0.8			Income tax expense
	$	—		$	(0.7	)	$	(1.4	)

(a) This AOCI component is included in the computation of net periodic pension benefit cost see Note 17, Employee Benefit Plans, for additional details.

Fair Value Measurement

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurement

Authoritative guidance establishes a valuation hierarchy for disclosure of the inputs to the valuation used to measure fair value. This hierarchy prioritizes the inputs into three broad levels as follows. Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3 inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value.

The following tables present information about our assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2019 and 2018, and indicate the fair value hierarchy of the valuation techniques we utilized to determine such fair value.



		Fair Value Measurement at December 31, 2019
Balance Sheet Classification	Type of Instrument	Total		Level 1		Level 2		Level 3
Cash equivalents	Money market funds	$	635.9	$	—	$	635.9	$	—
Cash equivalents	Commercial paper	$	227.9	$	—	$	227.9	$	—
Cash equivalents	Corporate bonds	$	20.6	$	—	$	20.6	$	—
Cash equivalents	Bank certificates of deposit	$	19.2	$	—	$	19.2	$	—
Cash equivalents	Other government-related obligations	$	60.4	$	—	$	60.4	$	—
Marketable securities	Mutual funds	$	23.1	$	23.1	$	—	$	—
Marketable securities	Commercial paper	$	19.0	$	—	$	19.0	$	—
Marketable securities	Corporate bonds	$	3.7	$	—	$	3.7	$	—
Marketable securities	Other government-related obligations	$	10.0	$	—	$	10.0	$	—
Marketable securities	Bank certificates of deposit	$	8.2	$	—	$	8.2	$	—
Other assets	Equity securities	$	79.0	$	51.2	$	27.8	$	—
Prepaid expenses and other current assets	Foreign exchange forward contracts	$	29.9	$	—	$	29.9	$	—
Other assets	Foreign exchange forward contracts	$	0.6	$	—	$	0.6	$	—
Other current liabilities	Foreign exchange forward contracts	$	26.6	$	—	$	26.6	$	—
Other liabilities	Foreign exchange forward contracts	$	1.1	$	—	$	1.1	$	—
Other current liabilities	Interest rate contracts	$	19.5	$	—	$	19.5	$	—
Other liabilities	Interest rate contracts	$	41.9	$	—	$	41.9	$	—
Contingent consideration	Acquisition-related contingent consideration	$	192.4	$	—	$	—	$	192.4
Other current liabilities	Other contingent payments	$	24.0	$	—	$	—	$	24.0



		Fair Value Measurement at December 31, 2018
Balance Sheet Classification	Type of Instrument	Total		Level 1		Level 2		Level 3
Cash equivalents	Money market funds	$	569.4	$	—	$	569.4	$	—
Cash equivalents	Commercial paper	$	35.4	$	—	$	35.4	$	—
Cash equivalents	Corporate bonds	$	0.2	$	—	$	0.2	$	—
Cash equivalents	Other government-related obligations	$	8.2	$	—	$	8.2	$	—
Marketable securities	Mutual funds	$	16.5	$	16.5	$	—	$	—
Marketable securities	Commercial paper	$	16.7	$	—	$	16.7	$	—
Marketable securities	Corporate bonds	$	122.6	$	—	$	122.6	$	—
Marketable securities	Other government-related obligations	$	9.3	$	—	$	9.3	$	—
Marketable securities	Bank certificates of deposit	$	33.2	$	—	$	33.2	$	—
Other assets	Equity securities	$	90.8	$	8.9	$	81.9	$	—
Prepaid expenses and other current assets	Foreign exchange forward contracts	$	40.5	$	—	$	40.5	$	—
Other assets	Foreign exchange forward contracts	$	0.3	$	—	$	0.3	$	—
Other current liabilities	Foreign exchange forward contracts	$	18.8	$	—	$	18.8	$	—
Other liabilities	Foreign exchange forward contracts	$	3.1	$	—	$	3.1	$	—
Prepaid expenses and other current assets	Interest rate contracts	$	20.1	$	—	$	20.1	$	—
Other current liabilities	Interest rate contracts	$	0.8	$	—	$	0.8	$	—
Other liabilities	Interest rate contracts	$	17.3	$	—	$	17.3	$	—
Current portion of contingent consideration	Acquisition-related contingent consideration	$	97.6	$	—	$	—	$	97.6
Contingent consideration	Acquisition-related contingent consideration	$	183.2	$	—	$	—	$	183.2

There were no securities transferred between Level 1, 2 and 3 during the year ended December 31, 2019.

Valuation Techniques

We classify mutual fund investments and equity securities, which are valued based on quoted market prices in active markets with no valuation adjustment, as Level 1 assets within the fair value hierarchy.

Cash equivalents and marketable securities classified as Level 2 within the valuation hierarchy include money market funds, commercial paper, U.S. and foreign government-related debt, corporate debt securities and certificates of deposit. We estimate the fair values of these marketable securities by taking into consideration valuations obtained from third-party pricing sources. These pricing sources utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include market pricing based on real-time trade data for similar securities, issuer credit spreads, benchmark yields, and other observable inputs. We validate the prices provided by our third-party pricing sources by understanding the models used, obtaining market values from other pricing sources and analyzing pricing data in certain instances.

Other investments in equity securities of publicly traded companies which are subject to holding period restrictions are carried at fair value using an option pricing valuation model and classified as Level 2 equity securities within the fair value hierarchy. The most significant assumptions within the option pricing valuation model are the term of the restrictions and the stock price volatility, which is based upon the historical volatility of the applicable company or similar companies. We also use a constant maturity risk-free interest rate to match the remaining term of the restrictions on such investments.

Our derivative assets and liabilities include foreign exchange and interest rate derivatives that are measured at fair value using observable market inputs such as forward rates, interest rates, our own credit risk as well as an evaluation of our counterparties’ credit risks. Based on these inputs, the derivative assets and liabilities are classified within Level 2 of the valuation hierarchy.

Contingent consideration liabilities related to business acquisitions and derivative liabilities associated with other contingent payments are classified as Level 3 within the valuation hierarchy and are valued based on various estimates, including probability of success, discount rates and amount of time until the conditions of the milestone payments are met.

As of December 31, 2019, there has not been any impact to the fair value of our derivative liabilities due to our own credit risk. Similarly, there has not been any significant adverse impact to our derivative assets based on our evaluation of our counterparties’ credit risks.

Acquisition-Related Contingent Consideration

In connection with prior business combinations, we may be required to pay future consideration that is contingent upon the achievement of specified development, regulatory approvals or sales-based milestone events. We determine the fair value of these obligations using various estimates that are not observable in the market and represent a Level 3 measurement within the fair value hierarchy. The resulting probability-weighted cash flows were discounted using a cost of debt ranging from 3.9% to 5.1% for developmental and regulatory milestones and a weighted average cost of capital ranging from 9.0% to 10.0% for sales-based milestones.

Each reporting period, we adjust the contingent consideration to fair value with changes in fair value recognized in operating earnings. Changes in fair values reflect new information about the probability and timing of meeting the conditions of the milestone payments. In the absence of new information, changes in fair value will only reflect the interest component of contingent consideration related to the passage of time.

As of December 31, 2019, estimated future contingent milestone payments related to prior business combinations range from zero if no milestone events are achieved, to a maximum of $602.0 if all development, regulatory and sales-based milestones are reached. In the second quarter 2019, a sales-based milestone associated with our acquisition of Enobia Pharma Corp. was achieved. In connection with such achievement, we made a $100.0 milestone payment in the third quarter 2019.

As of December 31, 2019, the fair value of acquisition-related contingent consideration was $192.4. The following table represents a roll-forward of our acquisition-related contingent consideration:



	2019
Balance at beginning of period	$	280.8
Milestone payments	(100.0		)
Changes in fair value	11.6
Balance at end of period	$	192.4

Other Contingent Payments

In January 2019, we entered into an agreement with Caelum, a biotechnology company that is developing CAEL-101 for light chain (AL) amyloidosis. Under the terms of the agreement, we acquired a minority equity interest in preferred stock of Caelum and an exclusive option to acquire the remaining equity in Caelum based on Phase II data, for pre-negotiated economics. We paid $30.0 during the first quarter 2019 and agreed to pay up to an additional $30.0 in contingent development milestones prior to our exercise of the option to acquire the remaining equity in Caelum. These contingent payments meet the definition of a derivative liability and were initially recorded at fair value of $27.1, based on the probability-weighted cash flows, discounted using a cost of debt ranging from 3.3% to 3.5%.

In December 2019, following FDA feedback which resulted in the redesign and expansion of Caelum’s planned clinical development program for CAEL-101, we amended the terms of our existing option agreement with Caelum. The amendment modified the terms of the option to acquire the remaining equity in Caelum based on data from the expanded Phase II/III trials. The amendment also modified the development-related milestone events associated with the initial $30.0 in contingent payments, provided for an additional $20.0 in upfront funding, which we accrued as of December 31, 2019, as well as funding of $60.0 in exchange for an additional equity interest at fair value upon achievement of

a specific development-related milestone event. Following the amendment, the $30.0 in contingent payments continues to meet the definition of a derivative liability.

Each reporting period, we adjust the derivative liability associated with the contingent payments to fair value with changes in fair value recognized in other income and expense. Changes in fair values reflect new information about the probability and timing of meeting the conditions of the milestone payments. In the absence of new information, changes in fair value will only reflect the interest component of the liability related to the passage of time. As of December 31, 2019, the fair value of our contingent payments was $24.0, based on the probability-weighted cash flows, discounted using a cost of debt of 2.1%. We recorded $3.1 in other income and (expense) during the year ended December 31, 2019 related to the change in the fair value of the liability, including $4.1 as a result of the amendment to our agreement with Caelum.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Employee Benefit Plans

12 Months Ended

Dec. 31, 2019

Retirement Benefits [Abstract]

Employee Benefit Plans

Deferred Compensation Plan

We have a nonqualified deferred compensation plan which allows certain highly-compensated employees to make voluntary deferrals of up to 80% of their base salary and incentive bonuses. The plan is designed to work in conjunction with the 401(k) plan and provides for a total combined employer match of up to 6% of an employee’s eligible earnings, up to the IRS annual 401(k) contribution limitations. Deferred compensation amounts under this plan as of December 31, 2019 and 2018 were $23.1 and $16.5, respectively, and are included in other liabilities within the consolidated balance sheets. Employer matching contributions under the plan for the years ended December 31, 2019, 2018 and 2017 were not material.

Defined Contribution Plan

We have one qualified 401(k) plan covering all eligible employees. Under the plan, employees may contribute up to the statutory allowable amount for any calendar year. We make matching contributions equal to $1.00 for each dollar contributed up to the first 6% of an individual’s base salary and incentive cash bonus up to the annual IRS maximum. For the years ended December 31, 2019, 2018 and 2017, we recorded matching contributions of approximately $18.9, $14.1, and $15.9 respectively.

Defined Benefit Plans

We maintain defined benefit plans for employees in certain countries outside the U.S., including retirement benefit plans required by applicable local law. The plans are valued by independent actuaries using the projected unit credit method. The liabilities correspond to the projected benefit obligations of which the discounted net present value is calculated based on years of employment, expected salary increases, and pension adjustments.

In 2018 and 2017 we recorded the impacts of a curtailment related to our Swiss plan as a result of a reduction of employees due to restructuring events as discussed in Note 18, Restructuring and Related Expenses.

The following table sets forth the funded status and the amounts recognized for defined benefit plans, including the impacts of the curtailments:



	December 31,
	2019		2018
Change in benefit obligation:
Projected benefit obligation, beginning of year	$	39.4	$	43.4
Service cost	6.0		6.3
Curtailment	—		(3.8		)
Other	9.6		(6.5		)
Projected benefit obligation, end of year	$	55.0	$	39.4
Accumulated benefit obligation, end of year	$	49.9	$	36.1



	December 31,
	2019			2018
Change in plan assets:
Fair value of plan assets, beginning of year	$	21.8		$	24.2
Employer contributions	3.4			3.0
Plan participants' contributions	1.4			1.3
Curtailment	—			(2.4		)
Other	0.7			(4.3		)
Fair value of plan assets, end of year	$	27.3		$	21.8
Funded status at end of year	$	(27.7	)	$	(17.6	)

The Company measures the fair value of plan assets based on the prices that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. All plan asset investments are classified as Level 2 within the fair value hierarchy and are valued utilizing observable prices for similar instruments and quoted prices for identical or similar instruments in markets that are not active. Plan assets are managed by an independent investment fiduciary and are primarily invested in debt and equity securities and real estate funds in order to maximize the overall return from investment income considering asset allocation limits as determined by pension law.

At December 31, 2019, we have recorded a liability of $27.7 in other noncurrent liabilities and an additional minimum liability of $9.2, net of tax, to accumulated other comprehensive income.

The following table provides the weighted average assumptions used to calculate net periodic benefit cost and the actuarial present value of projected benefit obligations:



	December 31,
	2019		2018
Weighted average assumptions - Net Periodic Benefit Cost:
Discount rate	0.8	%	0.8	%
Long term rate of return on assets	2.5	%	2.5	%
Rate of compensation increase	1.3	%	1.3	%
Weighted average assumptions - Projected Benefit Obligation:
Discount Rate	0.1	%	0.8	%
Rate of compensation increase	0.8	%	1.3	%

The discount rates used to determine the net periodic benefit cost and projected benefit obligation represent the yield on high quality AA-rated corporate bonds for periods that match the duration of the benefit obligations.

The expected long-term rate of return on plan assets represents a weighted average of expected returns per asset category. The rate of return considers historical and estimated future risk free rates of return as well as risk premiums for the relevant investment categories.

The components of net periodic benefit cost are as follows:



	Year Ended December 31,
	2019			2018			2017
Service cost	$	6.0		$	6.3		$	7.8
Employee contributions	(1.4		)	(1.3		)	(1.5		)
Amortization of prior service costs	(0.2		)	(0.3		)	(0.4		)
Curtailment	—			(0.8		)	(1.1		)
Amortization and deferral of actuarial gain	0.2			0.5			0.8
Other	(0.2		)	(0.3		)	(0.6		)
Total net periodic benefit cost	$	4.4		$	4.1		$	5.0

During 2019 service costs were recorded to operating expenses while all other components of the net periodic benefit was recorded to other income and expense within our consolidated statement of operations.

Other changes in plan assets and benefit obligations recognized in AOCI are as follows:



Amount included in AOCI - December 31, 2017	$	(4.8	)
Prior service cost	(0.3		)
Amortization of net gain	0.6
Curtailment	0.6
Taxes	(0.7		)
Other	2.0
Amount included in AOCI - December 31, 2018	$	(2.6	)
Prior service cost	(0.2		)
Amortization of net gain	0.2
Change in assumptions	(6.4		)
Taxes	2.1
Other	(2.3		)
Amount included in AOCI - December 31, 2019	$	(9.2	)

We estimate that we will pay employer contributions of approximately $2.6 in 2020. The expected future benefits to be paid in respect of the pension plans as of December 31, 2019 were as follows:



Year
2020	$	1.9
2021	1.8
2022	1.9
2023	1.8
2024	1.9
2025 to 2029	9.8

Restructuring and Related Expenses

12 Months Ended

Dec. 31, 2019

Restructuring and Related Activities [Abstract]

Restructuring and Related Expenses

In the first quarter 2019, we initiated corporate restructuring activities to re-align our international commercial organization through re-prioritization of certain geographical markets and to implement operational excellence through strategic reallocation of resources.

In the first quarter 2017, we initiated a company-wide restructuring designed to help position the Company for sustainable, long-term growth that we believe will further allow us to fulfill our mission of serving patients and families with rare diseases. In September 2017, we committed to an operational plan to re-align the global organization with its refocused corporate strategy. The re-alignment included the relocation of the Company's headquarters to Boston, Massachusetts and a reduction of the Company's global workforce. The restructuring was designed to result in cost

savings by focusing the development portfolio, simplifying business structures and process across the Company's global operations, and closing multiple Alexion sites.

The following table summarizes the total expenses recorded related to the restructuring activities by type of activity and the locations recognized within the consolidated statements of operations:



	December 31, 2019								December 31, 2018										December 31, 2017
	Employee Separation Costs		Asset-Related Charges		Other		Total		Employee Separation Costs		Asset-Related Charges		Other			Total			Employee Separation Costs		Asset-Related Charges		Other		Total
Cost of sales	$	—	$	—	$	—	$	—	$	—	$	5.8	$	—		$	5.8		$	—	$	152.1	$	—	$	152.1
Research and development	—		—		—		—		—		0.1		—			0.1			—		16.3		—		16.3
Selling, general and administrative	—		—		—		—		—		19.4		—			19.4			—		10.9		—		10.9
Restructuring expenses	8.4		—		3.6		12.0		4.6		—		20.9			25.5			87.3		—		17.3		104.6
Other income and (expense)	—		—		—		—		—		—		(0.1		)	(0.1		)	—		—		2.6		2.6
	$	8.4	$	—	$	3.6	$	12.0	$	4.6	$	25.3	$	20.8		$	50.7		$	87.3	$	179.3	$	19.9	$	286.5

Employee separation costs are associated with headcount reductions, as well as corporate employees not relocating to the Company's headquarters in 2018.

Asset-related charges consist of accelerated depreciation costs and asset impairment charges. Accelerated depreciation costs primarily relates to site closures, including ARIMF (which was sold to a third-party in 2018). Accelerated depreciation costs represent the difference between the depreciation expense recognized over the revised useful life of the asset, based upon the anticipated date the site closure, and the depreciation expense as determined using the useful life prior to the restructuring activities. Asset impairment charges primarily related to manufacturing assets that will no longer be utilized due to the 2017 restructuring activities.

Other costs consist of contract termination expenses, relocation costs, and other costs incurred as a direct result of an exit plan.

The following table presents a reconciliation of the restructuring reserve recorded within accounts payable and accrued expenses on the Company's consolidated balance sheets for the years ended December 31, 2019 and 2018:



	December 31, 2019											December 31, 2018
	Employee Separation Costs			Asset-Related Charges		Other			Total			Employee Separation Costs			Asset-Related Charges			Other			Total
Liability, beginning of year	$	4.2		$	—	$	—		$	4.2		$	53.8		$	—		$	4.4		$	58.2
Charges	14.2			—		3.0			17.2			5.8			25.3			21.1			52.2
Settlements	(9.3		)	—		(0.1		)	(9.4		)	(54.2		)	—			(25.2		)	(79.4		)
Adjustments to previous estimates	(5.8		)	—		0.6			(5.2		)	(1.2		)	—			(0.3		)	(1.5		)
Non Cash Activity	—			—		—			—			—			(25.3		)	—			(25.3		)
Liability, end of year	$	3.3		$	—	$	3.5		$	6.8		$	4.2		$	—		$	—		$	4.2

The restructuring reserve of $6.8 and $4.2 is recorded in accounts payable and accrued expenses on the Company's consolidated balance sheet as of December 31, 2019 and 2018, respectively. The accrued amounts are expected to be paid in the next twelve months. We estimate incurring an immaterial amount of additional restructuring expenses relating to the first quarter 2019 action.

Segment Information

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Segment Information

We operate in a single segment, focusing on serving patients affected by rare diseases through the discovery, development and commercialization of life-changing therapies. Consistent with our operational structure, our chief operating decision maker manages and allocates resources at a global, consolidated level. Therefore, results of our operations are reported on a consolidated basis for purposes of segment reporting, consistent with our management reporting. Disclosures about net product sales and long-lived assets by geographic area are presented below.

Net Product Sales

Net product sales by product and geographic region are as follows:



	Year Ended December 31,						% Change
	2019		2018		2017		2019 compared to 2018		2018 compared to 2017
SOLIRIS
United States	$	2,014.0	$	1,588.4	$	1,235.0	26.8	%	28.6	%
Europe	1,049.8		1,036.7		985.2		1.3	%	5.2	%
Asia Pacific	423.5		382.0		328.1		10.9	%	16.4	%
Rest of World	459.1		555.9		595.8		(17.4	)%	(6.7	)%
	$	3,946.4	$	3,563.0	$	3,144.1	10.8	%	13.3	%

ULTOMIRIS
United States	$	236.8	$	—	$	—	**		**
Europe	52.2		—		—		**		**
Asia Pacific	49.9		—		—		**		**
Rest of World	—		—		—		**		**
	$	338.9	$	—	$	—	**		**

STRENSIQ
United States	$	451.7	$	374.3	$	280.1	20.7	%	33.6	%
Europe	77.0		61.7		35.6		24.8	%	73.3	%
Asia Pacific	50.4		27.9		18.6		80.6	%	50.0	%
Rest of World	13.4		11.2		5.5		19.6	%	**
	$	592.5	$	475.1	$	339.8	24.7	%	39.8	%

KANUMA
United States	$	60.0	$	51.3	$	42.4	17.0	%	21.0	%
Europe	27.1		21.6		14.6		25.5	%	47.9	%
Asia Pacific	4.6		3.7		2.7		24.3	%	37.0	%
Rest of World	20.5		15.4		5.9		33.1	%	**
	$	112.2	$	92.0	$	65.6	22.0	%	40.2	%
Total Net Product Sales	4,990.0		$	4,130.1	$	3,549.5	20.8	%	16.4	%

** Percentages not meaningful

Long-Lived Assets

Long-lived assets consist of property, plant and equipment.



	December 31,
	2019		2018
United States	$	272.8	$	468.3
Europe	889.6		1,001.1
Other	0.9		2.1
	$	1,163.3	$	1,471.5

Quarterly Financial Information (unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information (unaudited)

The following condensed quarterly financial information is for the years ended December 31, 2019 and 2018:



	March 31			June 30			September 30		December 31
2019:
Total revenues	$	1,140.4		$	1,203.3		$	1,263.1	$	1,384.3
Cost of sales	85.8			99.2			95.2		114.3
Gross profit ^(A)	1,054.6			1,104.1			1,167.9		1,270.0
Operating expenses	537.8			571.5			637.9		729.0
Operating income	516.8			532.6			530.0		541.0
Net income	$	587.9	(1)	$	459.8		$	467.6	$	889.0		(2)
Earnings per common share
Basic	$	2.63		$	2.05		$	2.09	$	4.02
Diluted	$	2.61		$	2.04		$	2.08	$	4.00

	March 31			June 30			September 30		December 31
2018:
Total revenues	$	930.9		$	1,045.0		$	1,026.5	$	1,128.8
Cost of sales	91.6			95.3			90.6		96.8
Gross profit ^(A)	839.3			949.7			935.9		1,032.0
Operating expenses	571.9			1,349.8			577.3		988.3			(3)
Operating income (loss)	267.4			(400.1		)	358.6		43.7
Net income (loss)	$	249.1		$	(457.4	)	$	330.9	$	(45.0	)	(4)
Earnings (loss) per common share
Basic	$	1.12		$	(2.05	)	$	1.48	$	(0.20	)
Diluted	$	1.11		$	(2.05	)	$	1.47	$	(0.20	)

^{(A) Gross profit is calculated as total revenues less cost of sales}

(1) During the first quarter of 2019, we recognized one time tax benefits of $95.7 and $30.3 associated with a tax election made with respect to intellectual property of Wilson Therapeutics AB and a release of an existing valuation allowance, respectively. See Note 12, Income Taxes for additional information.

(2) During the fourth quarter of 2019, we recognized a one-time tax benefit of $382.2 related to an intra-entity asset transfer of certain intellectual property within our captive foreign partnership. See Note 12, Income Taxes for additional information.

(3) Included within operating expenses for the second and fourth quarter of 2018, we recognized $803.7 and $379.3, respectively, of acquired in-process research and development expense related to our Wilson and Syntimmune acquisitions, respectively. In connection with the agreement of the final working capital adjustment for the Syntimmune acquisition, we recognized a benefit of $4.1 associated with previously acquired in-process research and development in the second quarter 2019. See Note 2, Acquisitions for additional information.

(4) We recognized a tax benefit of $56.5 in 2018 as a result of the Tax Cuts and Jobs Act. In 2017, we recorded certain impacts of the Tax Act on a provisional basis. As of December 22, 2018, our accounting for the impact of the Tax Act was complete. See Note 12, Income Taxes for additional information.

Business Overview and Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Business Overview and Summary of Significant Accounting Policies [Abstract]

Business

Basis of Presentation and Principles of Consolidation

Dividend Policy

Critical Accounting Estimates

The most significant areas involving estimates, judgments and assumptions used in the preparation of our consolidated financial statements are as follows:


•	Revenue recognition;


•	Contingent liabilities;


•	Share-based compensation;


•	Valuation of goodwill, acquired intangible assets and in-process research and development (IPR&D);


•	Valuation of contingent consideration; and

•

Income taxes.

Foreign Currency Translation

Cash and Cash Equivalents

Fair Value of Financial Instruments

Marketable Securities

Accounts Receivable

Concentration of Credit Risk

Inventories

Inventories are stated at the lower of cost or net realizable value. Cost is determined in a manner that approximates average costs.

Capitalization of Inventory Costs

Inventory Write-Offs

Derivative Instruments

Property, Plant and Equipment

Property, plant and equipment are stated at cost and are depreciated on a straight-line basis over the estimated useful lives of the assets. We estimate economic lives as follows:


•	Building and improvements—fifteen to thirty five years


•	Machinery and laboratory equipment—five to fifteen years


•	Computer hardware and software—three to seven years


•	Furniture and office equipment— five to ten years

Construction-in-progress reflects amounts incurred for property, plant, or equipment construction or improvements that have not been placed in service.

Leases

Assets Held for Sale

Manufacturing Facilities

Acquisitions

Our consolidated financial statements include the results of operations of an acquired business after the completion of the acquisition.

Intangible Assets

Goodwill

Impairment of Long-Lived Assets

Contingent liabilities

Treasury Stock

Treasury stock is accounted for using the cost method, with the purchase price of the common stock recorded separately as a deduction from stockholders’ equity.

Revenue Recognition

Nature of Products

Variable Consideration

Variability in the transaction price for our products pursuant to our contracts with customers primarily arises from the following:

See Note 19, Segment Information for a summary of revenue from contracts with customers by product and geographical region.

Contract Balances and Receivables

Research and Development Expenses

Share-Based Compensation

Restructuring and Restructuring Related Expenses

Earnings Per Common Share

Certain items in the prior year’s consolidated financial statements have been reclassified to conform to the current presentation.

New Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Business Overview and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Business Overview and Summary of Significant Accounting Policies [Abstract]

Schedule of Inventories

The components of inventory are as follows:



	December 31,
	2019		2018
Raw materials	$	41.2	$	31.4
Work-in-process	180.8		90.4
Finished goods	405.6		350.7
	$	627.6	$	472.5

Schedule of the Calculation of Basic and Diluted EPS

The following table summarizes the calculation of basic and diluted EPS for years ended December 31, 2019, 2018 and 2017:



	Year Ended December 31,
	2019		2018		2017
Net income used for basic and diluted calculation	$	2,404.3	$	77.6	$	443.3
Shares used in computing earnings per common share—basic	223.2		222.7		223.9
Weighted-average effect of dilutive securities:
Stock awards	1.6		1.8		1.5
Shares used in computing earnings per common share—diluted	224.8		224.5		225.4
Earnings per common share:
Basic	$	10.77	$	0.35	$	1.98
Diluted	$	10.70	$	0.35	$	1.97

Acquisitions (Tables)

12 Months Ended

Dec. 31, 2019

Business Combinations [Abstract]

Schedule Of Asset Acquisition, By Acquisition [Table Text Block]



Consideration
Cash paid for acquisition of Wilson Therapeutics outstanding shares	$	749.3
Transaction costs	15.1
Total consideration	$	764.4

Assets Acquired and Liabilities Assumed
Cash	$	45.1
In-process research & development	803.7
Employee related liabilities	(71.4		)
Other assets and liabilities	(13.0		)
Total net assets acquired	$	764.4

Property, Plant and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2019

Property, Plant and Equipment, Net [Abstract]

Schedule of Property, Plant and Equipment

A summary of property, plant and equipment is as follows:



	December 31, 2019			December 31, 2018
Land	$	9.6		$	9.6
Buildings and improvements	208.7			520.1
Machinery and laboratory equipment	126.0			161.7
Computer hardware and software	155.1			144.8
Furniture and office equipment	23.4			27.5
Construction-in-progress	734.2			827.1
Financing lease right of use assets	127.2			—
	1,384.2			1,690.8
Less: Accumulated depreciation and amortization	(220.9		)	(219.3		)
	$	1,163.3		$	1,471.5

Intangible Assets and Goodwill (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Intangible Assets and Goodwill

The following table summarizes the carrying amount of our intangible assets and goodwill, net of accumulated amortization:



		December 31, 2019							December 31, 2018
	Estimated Life (years)	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net
Licensing Rights	3-8	$	57.0	$	(34.7	)	$	22.3	$	39.0	$	(29.3	)	$	9.7
Patents	7	10.5		(10.5		)	—		10.5		(10.5		)	—
Purchased technology	6-16	4,710.5		(1,388.7		)	3,321.8		4,710.5		(1,079.1		)	3,631.4
Other Intangibles	5	0.4		(0.2		)	0.2		0.4		(0.2		)	0.2
Total		$	4,778.4	$	(1,434.1	)	$	3,344.3	$	4,760.4	$	(1,119.1	)	$	3,641.3
Goodwill	Indefinite	$	5,040.3	$	(2.9	)	$	5,037.4	$	5,040.3	$	(2.9	)	$	5,037.4

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2019

Investments, Debt and Equity Securities [Abstract]

Schedule of Available-for-sale Securities Reconciliation [Table Text Block]



	December 31, 2019
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses		Fair Value
Commercial paper	$	246.9	$	—	$	—	$	246.9
Corporate bonds	24.3		—		—		24.3
Other government related obligations:
U.S.	70.4		—		—		70.4
Bank certificates of deposit	27.4		—		—		27.4
Total available-for-sale debt securities	$	369.0	$	—	$	—	$	369.0



	December 31, 2018
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Fair Value
Commercial paper	$	52.1	$	—	$	—		$	52.1
Corporate bonds	122.9		—		(0.1		)	122.8
Other government related obligations:
U.S.	17.5		—		—			17.5
Bank certificates of deposit	33.2		—		—			33.2
Total available-for-sale debt securities	$	225.7	$	—	$	(0.1	)	$	225.6

Available-for-sale Securities by Balance Sheet Location Classification [Table Text Block]

The fair values of available-for-sale debt securities by classification in the consolidated balance sheet were as follows:



	December 31, 2019		December 31, 2018
Cash and cash equivalents	$	328.1	$	43.8
Marketable securities	40.9		181.8
	$	369.0	$	225.6

Investments Classified by Contractual Maturity Date [Table Text Block]

The fair values of available-for-sale debt securities as of December 31, 2019, by contractual maturity, are summarized as follows:



	December 31, 2019
Due in one year or less	$	365.5
Due after one year through three years	3.5
Due after three years through five years	—
	$	369.0

Derivative Instruments and Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Interest Rate Derivatives [Table Text Block]

The following table summarizes the total interest rate swap contracts executed as of December 31, 2019:



Type of Interest Rate Swap	Notional Amount	Effective Date	Termination Date	Fixed Interest Rate or Rate Range
Floating to Fixed	450.0	December 2018	December 2022	2.60% - 2.79%
Floating to Fixed	1,300.0	December 2019	December 2022	2.37% - 2.83%

Schedule of Other Comprehensive Income and Earnings from Foreign Exchange Contracts



	Year ended December 31,
	2019					2018						2017
Financial Statement Line Item in which the Effects of Cash Flow Hedges are Recorded	Net Product Sales		Interest Expense			Net Product Sales			Interest Expense			Net Product Sales		Interest Expense
Total amount presented in the Consolidated Statements of Operations	$	4,990.0	$	(77.8	)	$	4,130.1		$	(98.2	)	$	3,549.5	$	(98.4	)
Impact of cash flow hedging relationships:
Foreign exchange forward contracts	$	36.8	$	—		$	(1.8	)	$	—		$	28.9	$	—
Interest rate swap contracts	$	—	$	13.3		$	—		$	13.6		$	—	$	(1.8	)



	Year Ended December 31,
	2019			2018			2017
Foreign Exchange Forward Contracts:
Gain (loss) recognized in AOCI, net of tax	$	27.9		$	37.7		$	(96.1	)
Gain (loss) reclassified from AOCI to net product sales, net of tax	$	28.4		$	(1.4	)	$	18.7
Interest Rate Swap Contracts:
Gain (loss) recognized in AOCI, net of tax	$	(39.0	)	$	(4.8	)	$	7.9
Gain (loss) reclassified from AOCI to interest expense, net of tax	$	10.2		$	10.8		$	(1.1	)

Schedule of Fair Value of Outstanding Derivatives

The following tables summarize the fair value of outstanding derivatives at December 31, 2019 and 2018:



	December 31, 2019
	Asset Derivatives			Liability Derivatives
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Derivatives designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	$	12.7	Other current liabilities	$	6.2
Foreign exchange forward contracts	Other assets	0.6		Other liabilities	1.1
Interest rate contracts	Prepaid expenses and other current assets	—		Other current liabilities	19.5
Interest rate contracts	Other assets	—		Other liabilities	41.9
Derivatives not designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	17.2		Other current liabilities	20.4
Total fair value of derivative instruments		$	30.5		$	89.1



	December 31, 2018
	Asset Derivatives			Liability Derivatives
	Balance Sheet Location	Fair Value		Balance Sheet Location	Fair Value
Derivatives designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	$	16.9	Other current liabilities	$	7.3
Foreign exchange forward contracts	Other assets	0.3		Other liabilities	3.1
Interest rate contracts	Prepaid expenses and other current assets	20.1		Other current liabilities	0.8
Interest rate contracts	Other assets	—		Other liabilities	17.3
Derivatives not designated as hedging instruments:
Foreign exchange forward contracts	Prepaid expenses and other current assets	23.6		Other current liabilities	11.5
Total fair value of derivative instruments		$	60.9		$	40.0

Offsetting Assets and Liabilities [Table Text Block]

The following tables summarize the potential effect on our condensed consolidated balance sheets of offsetting our foreign exchange forward contracts and interest rate contracts subject to such provisions:



December 31, 2019
								Gross Amounts Not Offset in the Consolidated Balance Sheet
Description	Gross Amounts of Recognized Assets/Liabilities			Gross Amounts Offset in the Consolidated Balance Sheet	Net Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheet			Derivative Financial Instruments			Cash Collateral Received (Pledged)		Net Amount
Derivative assets	$	30.5			$	30.5		$	(21.4	)	$	—	$	9.1
Derivative liabilities	$	(89.1	)		$	(89.1	)	$	21.4		$	—	$	(67.7	)



December 31, 2018
									Gross Amounts Not Offset in the Consolidated Balance Sheet
Description	Gross Amounts of Recognized Assets/Liabilities			Gross Amounts Offset in the Consolidated Balance Sheet		Net Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheet			Derivative Financial Instruments			Cash Collateral Received (Pledged)		Net Amount
Derivative assets	$	60.9		$	—	$	60.9		$	(30.2	)	$	—	$	30.7
Derivative liabilities	$	(40.0	)	$	—	$	(40.0	)	$	30.2		$	—	$	(9.8	)

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2019

Accrued Liabilities [Abstract]

Schedule of Accrued Expenses

Accounts payable and accrued expenses consist of the following:



	December 31, 2019		December 31, 2018
Accounts Payable	$	74.0	$	74.4
Royalties	20.1		27.0
Payroll and employee benefits	191.3		170.4
Taxes payable	103.9		24.4
Rebates payable	250.1		122.8
Clinical	67.3		58.6
Manufacturing	72.8		72.0
Accrued restructuring costs	6.8		4.2
Other	180.4		144.4
	$	966.7	$	698.2

Debt Debt (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of Maturities of Long-term Debt

The contractual maturities of our long-term debt obligations due subsequent to December 31, 2019 are as follows:



Year
2020	$	130.6
2021	130.6
2022	130.6
2023	2,122.7
2024	—

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Schedule of Lease Assets and Lease Liabilities

The following table summarizes our lease assets and liabilities as of December 31, 2019:



ROU Assets and Liabilities
	Balance Sheet Location	Financing		Operating
ROU - Asset	Right of use operating assets	$	—	$	204.0
ROU - Asset	Property, plant, and equipment	$	116.3	—
Lease liabilities (current)	Other current liabilities	$	5.2	18.8
Lease liabilities (noncurrent)	Noncurrent operating lease liabilities	$	—	164.1
Lease liabilities (noncurrent)	Other liabilities	$	72.9	—

Summary of Lease Costs

The following table summarizes our lease related costs for the twelve months ended December 31, 2019:



Lease Cost
	Statement of Operations Location	Twelve months ended
		December 31, 2019
Financing Lease Cost		$	14.8
Amortization of ROU Assets	Operating Expenses	10.9
Interest on Lease Liabilities	Interest Expense	3.9
Operating Lease Cost	Operating Expenses	34.3
Variable Lease Cost	Operating Expenses	11.8
Total Lease Cost		$	60.9

Schedule of Lease Cash Flow Information

The following table summarizes supplemental cash flow information for the twelve months ended December 31, 2019:



Other Information
	Twelve months ended
	December 31, 2019
Cash Paid For Amounts Included In Measurement of Liabilities	$	32.3
Operating Cash Flows From Financing Leases	3.9
Operating Cash Flows From Operating Leases	23.5
Financing Cash Flows From Financing Leases	4.9
ROU Assets Obtained In Exchange For New Financing Liabilities ⁽¹⁾	—
ROU Assets Obtained In Exchange For New Operating Liabilities ⁽²⁾	27.5

(1) We capitalized $83.1 of ROU financing assets upon adoption of the new lease standard in the first quarter of 2019 that are excluded from the figures for the twelve months ended December 31, 2019. This figure excludes $44.2 of opening adjustments to ROU finance assets related, primarily, to prepayments of rent.
(2) We capitalized $172.2 of ROU operating assets upon adoption of the new lease standard in the first quarter of 2019 that are excluded from the figures for the twelve months ended December 31, 2019. This figure excludes $26.6 of opening adjustments to ROU operating assets related, primarily, to prepayments of rent.

Schedule of Financing Lease Liability Maturities

The following tables summarize maturities of lease liabilities and the reconciliation of lease liabilities as of December 31, 2019:



Lease Liability Maturity Summary
Year	Financing		Operating		Total
2020	$	8.8	$	25.7	$	34.5
2021	9.0		23.0		32.0
2022	9.2		21.6		30.8
2023	9.2		20.9		30.1
2024	9.4		20.3		29.7
Thereafter	54.6		112.1		166.7

Schedule of Operating Lease Liability Maturities

The following tables summarize maturities of lease liabilities and the reconciliation of lease liabilities as of December 31, 2019:



Lease Liability Maturity Summary
Year	Financing		Operating		Total
2020	$	8.8	$	25.7	$	34.5
2021	9.0		23.0		32.0
2022	9.2		21.6		30.8
2023	9.2		20.9		30.1
2024	9.4		20.3		29.7
Thereafter	54.6		112.1		166.7

Schedule of Operating and Finance Lease Additional Information



Reconciliation of Lease Liabilities	Financing			Operating			Total
Weighted-average Remaining Lease Term (years)	10.67			10.17			10.32
Weighted-average Discount Rate	4.85		%	4.10		%	4.33		%

Total Undiscounted Lease Liability	$	100.2		$	223.6		$	323.8
Imputed Interest	22.1			40.7			62.8
Total Discounted Lease Liability	78.1			182.9			261.0

Schedule of Aggregate Future Minimum Annual Rental Payments

For comparable purposes, our aggregate future minimum non-cancellable commitments under leases as of December 31, 2018 were as follows:



Year
2019	$	27.8
2020	24.7
2021	21.3
2022	19.9
2023	19.7
Thereafter	132.2

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Schedule of Income Tax Provision (Benefit) on Income Before Income Taxes

Income tax expense is based on income before income taxes as follows:



	Year Ended December 31,
	2019		2018			2017
U.S.	$	2.0	$	(451.4	)	$	(43.9	)
Non-U.S.	2,176.8		693.6			591.7
	$	2,178.8	$	242.2		$	547.8

Schedule of Components of Income Tax Provision (Benefit)

The components of income tax expense are as follows:



	Year Ended December 31,
	2019			2018			2017
Domestic
Current	$	71.8		$	57.0		$	42.9
Deferred	1,731.0			49.5			7.2
	1,802.8			106.5			50.1
Foreign
Current	158.2			74.7			107.5
Deferred	(2,186.5		)	(16.6		)	(53.1		)
	(2,028.3		)	58.1			54.4
Total
Current	230.0			131.7			150.4
Deferred	(455.5		)	32.9			(45.9		)
	$	(225.5	)	$	164.6		$	104.5

Reconciliation of the Statutory U.S. Federal Income Tax Rate to Effective Income Tax Rate

The reconciliation of the statutory U.S. federal income tax rate to our effective income tax rate is as follows:



	Year Ended December 31,
	2019		2018		2017
U.S. federal statutory tax rate	21.0	%	21.0	%	35.0	%
Benefit of foreign earnings	(12.6	)%	(71.2	)%	60.1	%
Tax credits	(0.7	)%	(17.0	)%	(10.7	)%
Tax reserves	(0.1	)%	12.1	%	(14.0	)%
Re-measurement of deferred taxes as a result of the Tax Act	—	%	—	%	(53.4	)%
Acquired in-process research & development	—	%	102.6	%	—	%
Intra-entity asset transfer of intellectual property	(17.5	)%	—	%	—	%
Foreign-derived intangible income	(1.6	)%	(4.5	)%	—	%
U.S. state taxes	0.7	%	14.2	%	1.5	%
Other permanent differences	0.5	%	10.8	%	0.6	%

Effective Income Tax Rate	(10.3	)%	68.0	%	19.1	%

Schedule of Components of Deferred Tax Assets and Liabilities

The components of the deferred tax assets and liabilities are as follows:



	December 31,			December 31,
	2019			2018
Deferred tax assets:
Net operating losses	$	102.9		$	41.8
Income tax credits	328.1			371.6
Stock compensation	57.1			47.6
Accruals and allowances	65.2			105.8
Unrealized losses	18.8			—
Research and development expenses	3.5			5.2
Accrued royalties	0.8			89.1
ROU leases	46.2			—
Intangible assets	1,967.3			—
	2,589.9			661.1
Valuation allowance	(72.6		)	(19.6		)
Total deferred tax assets	2,517.3			641.5
Deferred tax liabilities:
Depreciable assets	(5.1		)	(88.7		)
Unrealized gains	—			(6.6		)
Investment in foreign partnership	(2,249.5		)	(566.6		)
ROU leases	(53.9		)	—
Intangible liabilities	—			(268.8		)
Total deferred tax liabilities	(2,308.5		)	(930.7		)
Net deferred tax (liability) asset	$	208.8		$	(289.2	)

Reconciliation of Unrecognized Tax Benefits

The beginning and ending amounts of unrecognized tax benefits reconciles as follows:



	2019			2018			2017
Beginning of period balance	$	92.7		$	60.9		$	138.9
Increases for tax positions taken during a prior period	3.4			9.1			5.6
Decreases for tax positions taken during a prior period	(4.9		)	(5.8		)	(85.8		)
Increases for tax positions taken during the current period	43.8			28.8			19.3
Decreases for tax positions related to settlements	—			—			(15.8		)
Decreases for tax positions related to lapse of statute	(1.2		)	(0.3		)	(1.3		)
	$	133.8		$	92.7		$	60.9

Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-Based Compensation

The following table summarizes the share-based compensation expense in the consolidated statements of operations:



	Year Ended December 31,
	2019			2018			2017
Cost of sales	$	14.1		$	16.0		$	11.1
Research and development	61.8			57.5			76.4
Selling, general and administrative	161.1			129.5			155.6
Total share-based compensation expense	237.0			203.0			243.1
Income tax effect	(55.0		)	(46.5		)	(89.3		)
Total share-based compensation expense, net of tax	$	182.0		$	156.5		$	153.8

Schedule of Share-based Compensation, Stock Options, Activity

A summary of the status of our stock options at December 31, 2019, and changes during the year then ended is presented in the table and narrative below:



	Number of shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value
Outstanding at December 31, 2018	3.6		$	119.68
Granted	—		—
Exercised	(0.3	)	67.87
Forfeited and canceled	(0.3	)	158.71
Outstanding at December 31, 2019	3.0		$	119.51	4.08	$	49.0
Vested and unvested expected to vest at December 31, 2019	3.0		$	119.49	4.07	$	49.0
Exercisable at December 31, 2019	2.9		$	119.15	3.93	$	48.9

Schedule of Share-based Compensation Valuation Assumptions

the fair value of options at the date of grant was estimated using the Black-Scholes model with the following ranges of weighted average assumptions:



	December 31,
	2017
Expected life in years	4.07 - 4.29
Interest rate	1.64% - 1.92%
Volatility	38.78% - 39.01%
Dividend yield	—

Schedule of Share-based Compensation, Restricted Stock Activity

A summary of the status of our nonvested Restricted Stock at December 31, 2019 and changes during the year then ended is as follows:



	Number of Shares	Weighted Average Grant Date Fair Value
Nonvested Restricted Stock at December 31, 2018	3.7	$	123.25
Shares granted	2.4	133.89
Shares forfeited	0.5	126.76
Shares vested	1.3	125.02
Nonvested Restricted Stock at December 31, 2019	4.3	$	128.24

Other Comprehensive Income and Accumulated Other Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2019

Other Comprehensive Income and Accumulated Other Comprehensive Income [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The following table summarizes the changes in AOCI, by component, for the years ended December 31, 2019, 2018 and 2017:



	Defined Benefit Pension Plans			Unrealized Gains (Losses) from Debt Securities			Unrealized Gains (Losses) from Hedging Activities			Foreign Currency Translation Adjustment			Total Accumulated Other Comprehensive Income (Loss)
Balances, December 31, 2016	$	(6.7	)	$	(0.4	)	$	91.9		$	(24.3	)	$	60.5
Other comprehensive income (loss) before reclassifications	0.5			(0.2		)	(88.2		)	8.4			(79.5		)
Amounts reclassified from other comprehensive income	1.4			0.8			(17.6		)	—			(15.4		)
Net other comprehensive income (loss)	1.9			0.6			(105.8		)	8.4			(94.9		)
Balances, December 31, 2017	$	(4.8	)	$	0.2		$	(13.9	)	$	(15.9	)	$	(34.4	)
Other comprehensive income (loss) before reclassifications	1.5			0.1			32.9			(0.5		)	34.0
Amounts reclassified from other comprehensive income	0.7			(0.6		)	(9.4		)	—			(9.3		)
Net other comprehensive income (loss)	2.2			(0.5		)	23.5			(0.5		)	24.7
Balances, December 31, 2018	$	(2.6	)	$	(0.3	)	$	9.6		$	(16.4	)	$	(9.7	)
Other comprehensive income (loss) before reclassifications	(6.6		)	0.2			(11.1		)	(1.0		)	(18.5		)
Amounts reclassified from other comprehensive income	—			—			(38.6		)	—			(38.6		)
Net other comprehensive income (loss)	(6.6		)	0.2			(49.7		)	(1.0		)	(57.1		)
Balances, December 31, 2019	$	(9.2	)	$	(0.1	)	$	(40.1	)	$	(17.4	)	$	(66.8	)

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

The table below provides details regarding significant reclassifications from AOCI during the years ended December 31, 2019, 2018 and 2017:



Details about Accumulated Other Comprehensive Income Components	Amount Reclassified From Accumulated Other Comprehensive Income during the year ended December 31,									Affected Line Item in the Consolidated Statements of Operations
	2019			2018			2017
Unrealized Gains (Losses) on Hedging Activity
Forward exchange forward contracts	$	36.8		$	(1.8	)	$	28.9		Net product sales
Interest rate swap contracts	13.3			13.6			(1.8		)	Interest expense
	50.1			11.8			27.1
	(11.5		)	(2.4		)	(9.5		)	Income tax (benefit) expense
	$	38.6		$	9.4		$	17.6
Defined Benefit Pension Items
Amortization of prior service costs and actuarial losses	$	—		$	(0.3	)	$	(0.4	)	^(a)
Curtailment	—			(0.6		)	(1.8		)	^(a)
	—			(0.9		)	(2.2		)
	—			0.2			0.8			Income tax expense
	$	—		$	(0.7	)	$	(1.4	)

(a) This AOCI component is included in the computation of net periodic pension benefit cost see Note 17, Employee Benefit Plans, for additional details.

Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Schedule Of Assets And Liabilites Measured At Fair Value

December 31, 2019 and 2018, and indicate the fair value hierarchy of the valuation techniques we utilized to determine such fair value.



		Fair Value Measurement at December 31, 2019
Balance Sheet Classification	Type of Instrument	Total		Level 1		Level 2		Level 3
Cash equivalents	Money market funds	$	635.9	$	—	$	635.9	$	—
Cash equivalents	Commercial paper	$	227.9	$	—	$	227.9	$	—
Cash equivalents	Corporate bonds	$	20.6	$	—	$	20.6	$	—
Cash equivalents	Bank certificates of deposit	$	19.2	$	—	$	19.2	$	—
Cash equivalents	Other government-related obligations	$	60.4	$	—	$	60.4	$	—
Marketable securities	Mutual funds	$	23.1	$	23.1	$	—	$	—
Marketable securities	Commercial paper	$	19.0	$	—	$	19.0	$	—
Marketable securities	Corporate bonds	$	3.7	$	—	$	3.7	$	—
Marketable securities	Other government-related obligations	$	10.0	$	—	$	10.0	$	—
Marketable securities	Bank certificates of deposit	$	8.2	$	—	$	8.2	$	—
Other assets	Equity securities	$	79.0	$	51.2	$	27.8	$	—
Prepaid expenses and other current assets	Foreign exchange forward contracts	$	29.9	$	—	$	29.9	$	—
Other assets	Foreign exchange forward contracts	$	0.6	$	—	$	0.6	$	—
Other current liabilities	Foreign exchange forward contracts	$	26.6	$	—	$	26.6	$	—
Other liabilities	Foreign exchange forward contracts	$	1.1	$	—	$	1.1	$	—
Other current liabilities	Interest rate contracts	$	19.5	$	—	$	19.5	$	—
Other liabilities	Interest rate contracts	$	41.9	$	—	$	41.9	$	—
Contingent consideration	Acquisition-related contingent consideration	$	192.4	$	—	$	—	$	192.4
Other current liabilities	Other contingent payments	$	24.0	$	—	$	—	$	24.0



		Fair Value Measurement at December 31, 2018
Balance Sheet Classification	Type of Instrument	Total		Level 1		Level 2		Level 3
Cash equivalents	Money market funds	$	569.4	$	—	$	569.4	$	—
Cash equivalents	Commercial paper	$	35.4	$	—	$	35.4	$	—
Cash equivalents	Corporate bonds	$	0.2	$	—	$	0.2	$	—
Cash equivalents	Other government-related obligations	$	8.2	$	—	$	8.2	$	—
Marketable securities	Mutual funds	$	16.5	$	16.5	$	—	$	—
Marketable securities	Commercial paper	$	16.7	$	—	$	16.7	$	—
Marketable securities	Corporate bonds	$	122.6	$	—	$	122.6	$	—
Marketable securities	Other government-related obligations	$	9.3	$	—	$	9.3	$	—
Marketable securities	Bank certificates of deposit	$	33.2	$	—	$	33.2	$	—
Other assets	Equity securities	$	90.8	$	8.9	$	81.9	$	—
Prepaid expenses and other current assets	Foreign exchange forward contracts	$	40.5	$	—	$	40.5	$	—
Other assets	Foreign exchange forward contracts	$	0.3	$	—	$	0.3	$	—
Other current liabilities	Foreign exchange forward contracts	$	18.8	$	—	$	18.8	$	—
Other liabilities	Foreign exchange forward contracts	$	3.1	$	—	$	3.1	$	—
Prepaid expenses and other current assets	Interest rate contracts	$	20.1	$	—	$	20.1	$	—
Other current liabilities	Interest rate contracts	$	0.8	$	—	$	0.8	$	—
Other liabilities	Interest rate contracts	$	17.3	$	—	$	17.3	$	—
Current portion of contingent consideration	Acquisition-related contingent consideration	$	97.6	$	—	$	—	$	97.6
Contingent consideration	Acquisition-related contingent consideration	$	183.2	$	—	$	—	$	183.2

Schedule Of Acquisition-Related Contingent Consideration

The following table represents a roll-forward of our acquisition-related contingent consideration:



	2019
Balance at beginning of period	$	280.8
Milestone payments	(100.0		)
Changes in fair value	11.6
Balance at end of period	$	192.4

Employee Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2019

Retirement Benefits [Abstract]

Schedule of Change in Benefit Obligation

The following table sets forth the funded status and the amounts recognized for defined benefit plans, including the impacts of the curtailments:



	December 31,
	2019		2018
Change in benefit obligation:
Projected benefit obligation, beginning of year	$	39.4	$	43.4
Service cost	6.0		6.3
Curtailment	—		(3.8		)
Other	9.6		(6.5		)
Projected benefit obligation, end of year	$	55.0	$	39.4
Accumulated benefit obligation, end of year	$	49.9	$	36.1

Schedule of Change in Plan Assets



	December 31,
	2019			2018
Change in plan assets:
Fair value of plan assets, beginning of year	$	21.8		$	24.2
Employer contributions	3.4			3.0
Plan participants' contributions	1.4			1.3
Curtailment	—			(2.4		)
Other	0.7			(4.3		)
Fair value of plan assets, end of year	$	27.3		$	21.8
Funded status at end of year	$	(27.7	)	$	(17.6	)

Schedule of Weighted Average Assumptions Used to Calculate Net Periodic Benefit Cost and the Actuarial Present Value of Projected Benefit Obligations

The following table provides the weighted average assumptions used to calculate net periodic benefit cost and the actuarial present value of projected benefit obligations:



	December 31,
	2019		2018
Weighted average assumptions - Net Periodic Benefit Cost:
Discount rate	0.8	%	0.8	%
Long term rate of return on assets	2.5	%	2.5	%
Rate of compensation increase	1.3	%	1.3	%
Weighted average assumptions - Projected Benefit Obligation:
Discount Rate	0.1	%	0.8	%
Rate of compensation increase	0.8	%	1.3	%

Schedule of Components of Net Periodic Benefit Costs

The components of net periodic benefit cost are as follows:



	Year Ended December 31,
	2019			2018			2017
Service cost	$	6.0		$	6.3		$	7.8
Employee contributions	(1.4		)	(1.3		)	(1.5		)
Amortization of prior service costs	(0.2		)	(0.3		)	(0.4		)
Curtailment	—			(0.8		)	(1.1		)
Amortization and deferral of actuarial gain	0.2			0.5			0.8
Other	(0.2		)	(0.3		)	(0.6		)
Total net periodic benefit cost	$	4.4		$	4.1		$	5.0

Schedule of Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income

Other changes in plan assets and benefit obligations recognized in AOCI are as follows:



Amount included in AOCI - December 31, 2017	$	(4.8	)
Prior service cost	(0.3		)
Amortization of net gain	0.6
Curtailment	0.6
Taxes	(0.7		)
Other	2.0
Amount included in AOCI - December 31, 2018	$	(2.6	)
Prior service cost	(0.2		)
Amortization of net gain	0.2
Change in assumptions	(6.4		)
Taxes	2.1
Other	(2.3		)
Amount included in AOCI - December 31, 2019	$	(9.2	)

Schedule of Estimated Future Benefit Payments

The expected future benefits to be paid in respect of the pension plans as of December 31, 2019 were as follows:



Year
2020	$	1.9
2021	1.8
2022	1.9
2023	1.8
2024	1.9
2025 to 2029	9.8

Restructuring and Related Expenses (Tables)

12 Months Ended

Dec. 31, 2019

Restructuring and Related Activities [Abstract]

Restructuring and Related Costs [Table Text Block]

The following table summarizes the total expenses recorded related to the restructuring activities by type of activity and the locations recognized within the consolidated statements of operations:



	December 31, 2019								December 31, 2018										December 31, 2017
	Employee Separation Costs		Asset-Related Charges		Other		Total		Employee Separation Costs		Asset-Related Charges		Other			Total			Employee Separation Costs		Asset-Related Charges		Other		Total
Cost of sales	$	—	$	—	$	—	$	—	$	—	$	5.8	$	—		$	5.8		$	—	$	152.1	$	—	$	152.1
Research and development	—		—		—		—		—		0.1		—			0.1			—		16.3		—		16.3
Selling, general and administrative	—		—		—		—		—		19.4		—			19.4			—		10.9		—		10.9
Restructuring expenses	8.4		—		3.6		12.0		4.6		—		20.9			25.5			87.3		—		17.3		104.6
Other income and (expense)	—		—		—		—		—		—		(0.1		)	(0.1		)	—		—		2.6		2.6
	$	8.4	$	—	$	3.6	$	12.0	$	4.6	$	25.3	$	20.8		$	50.7		$	87.3	$	179.3	$	19.9	$	286.5



	December 31, 2019											December 31, 2018
	Employee Separation Costs			Asset-Related Charges		Other			Total			Employee Separation Costs			Asset-Related Charges			Other			Total
Liability, beginning of year	$	4.2		$	—	$	—		$	4.2		$	53.8		$	—		$	4.4		$	58.2
Charges	14.2			—		3.0			17.2			5.8			25.3			21.1			52.2
Settlements	(9.3		)	—		(0.1		)	(9.4		)	(54.2		)	—			(25.2		)	(79.4		)
Adjustments to previous estimates	(5.8		)	—		0.6			(5.2		)	(1.2		)	—			(0.3		)	(1.5		)
Non Cash Activity	—			—		—			—			—			(25.3		)	—			(25.3		)
Liability, end of year	$	3.3		$	—	$	3.5		$	6.8		$	4.2		$	—		$	—		$	4.2

Segment Information (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Schedule of Revenues and Tangible Long-Lived Assets by Significant Geographic Region

Long-lived assets consist of property, plant and equipment.



	December 31,
	2019		2018
United States	$	272.8	$	468.3
Europe	889.6		1,001.1
Other	0.9		2.1
	$	1,163.3	$	1,471.5

Net product sales by product and geographic region are as follows:



	Year Ended December 31,						% Change
	2019		2018		2017		2019 compared to 2018		2018 compared to 2017
SOLIRIS
United States	$	2,014.0	$	1,588.4	$	1,235.0	26.8	%	28.6	%
Europe	1,049.8		1,036.7		985.2		1.3	%	5.2	%
Asia Pacific	423.5		382.0		328.1		10.9	%	16.4	%
Rest of World	459.1		555.9		595.8		(17.4	)%	(6.7	)%
	$	3,946.4	$	3,563.0	$	3,144.1	10.8	%	13.3	%

ULTOMIRIS
United States	$	236.8	$	—	$	—	**		**
Europe	52.2		—		—		**		**
Asia Pacific	49.9		—		—		**		**
Rest of World	—		—		—		**		**
	$	338.9	$	—	$	—	**		**

STRENSIQ
United States	$	451.7	$	374.3	$	280.1	20.7	%	33.6	%
Europe	77.0		61.7		35.6		24.8	%	73.3	%
Asia Pacific	50.4		27.9		18.6		80.6	%	50.0	%
Rest of World	13.4		11.2		5.5		19.6	%	**
	$	592.5	$	475.1	$	339.8	24.7	%	39.8	%

KANUMA
United States	$	60.0	$	51.3	$	42.4	17.0	%	21.0	%
Europe	27.1		21.6		14.6		25.5	%	47.9	%
Asia Pacific	4.6		3.7		2.7		24.3	%	37.0	%
Rest of World	20.5		15.4		5.9		33.1	%	**
	$	112.2	$	92.0	$	65.6	22.0	%	40.2	%
Total Net Product Sales	4,990.0		$	4,130.1	$	3,549.5	20.8	%	16.4	%

** Percentages not meaningful

Quarterly Financial Information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Schedule of Condensed Quarterly Financial Information

The following condensed quarterly financial information is for the years ended December 31, 2019 and 2018:



	March 31			June 30			September 30		December 31
2019:
Total revenues	$	1,140.4		$	1,203.3		$	1,263.1	$	1,384.3
Cost of sales	85.8			99.2			95.2		114.3
Gross profit ^(A)	1,054.6			1,104.1			1,167.9		1,270.0
Operating expenses	537.8			571.5			637.9		729.0
Operating income	516.8			532.6			530.0		541.0
Net income	$	587.9	(1)	$	459.8		$	467.6	$	889.0		(2)
Earnings per common share
Basic	$	2.63		$	2.05		$	2.09	$	4.02
Diluted	$	2.61		$	2.04		$	2.08	$	4.00

	March 31			June 30			September 30		December 31
2018:
Total revenues	$	930.9		$	1,045.0		$	1,026.5	$	1,128.8
Cost of sales	91.6			95.3			90.6		96.8
Gross profit ^(A)	839.3			949.7			935.9		1,032.0
Operating expenses	571.9			1,349.8			577.3		988.3			(3)
Operating income (loss)	267.4			(400.1		)	358.6		43.7
Net income (loss)	$	249.1		$	(457.4	)	$	330.9	$	(45.0	)	(4)
Earnings (loss) per common share
Basic	$	1.12		$	(2.05	)	$	1.48	$	(0.20	)
Diluted	$	1.11		$	(2.05	)	$	1.47	$	(0.20	)

^{(A) Gross profit is calculated as total revenues less cost of sales}

Business Overview and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Jan. 01, 2018
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross	$ 1,384.2				$ 1,690.8				$ 1,384.2	$ 1,690.8
Inventories	627.6				472.5				627.6	472.5
Impairment of intangible assets									$ 0.0	0.0	$ 31.0
Purchase per share of fair market value of common stock (percent) (lower of)									85.00%
ESPP, discount (percent)									15.00%
Facility Lease Obligation, Noncurrent	0.0				361.0				$ 0.0	361.0
Right of use operating assets	204.0				0.0				204.0	0.0
Operating Lease, Liability	182.9								182.9
Adoption of new guidance, value	(90.3)				6.1				(90.3)	6.1	(18.8)
Retained Earnings (Accumulated Deficit)	4,639.8				2,325.8				4,639.8	2,325.8
Total revenues	1,384.3	$ 1,263.1	$ 1,203.3	$ 1,140.4	1,128.8	$ 1,026.5	$ 1,045.0	$ 930.9	4,991.1	4,131.2	3,551.1
Net income (loss)	889.0	$ 467.6	$ 459.8	587.9	(45.0)	$ 330.9	$ (457.4)	$ 249.1	$ 2,404.3	$ 77.6	$ 443.3
Minimum
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Accounts Receivable, Standard Credit Term									30 days
Accounts Receivable, Consolidated Average Term of Sales Outstanding									70 days
Inventory estimated life (in months)									36 months
Minimum \| Building and improvements
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									15 years
Minimum \| Machinery and laboratory equipment
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									5 years
Minimum \| Computer hardware and software
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									3 years
Minimum \| Furniture and office equipment
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									5 years
Maximum
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Accounts Receivable, Standard Credit Term									120 days
Accounts Receivable, Consolidated Average Term of Sales Outstanding									80 days
Inventory estimated life (in months)									48 months
Maximum \| Building and improvements
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									35 years
Maximum \| Machinery and laboratory equipment
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									15 years
Maximum \| Computer hardware and software
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									7 years
Maximum \| Furniture and office equipment
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Useful life									10 years
Customer Concentration Risk \| Four Largest Customers [Member] [Member] \| Accounts Receivable [Member]
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Percentage change in product sales									66.90%
Customer Concentration Risk \| Three Largest Customers [Member] \| Accounts Receivable [Member]
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Percentage change in product sales										48.70%
Customer Concentration Risk \| Three Largest Customers [Member] \| Accounts Receivable [Member] \| Minimum
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Percentage change in product sales									11.60%	14.00%
Customer Concentration Risk \| Three Largest Customers [Member] \| Accounts Receivable [Member] \| Maximum
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Percentage change in product sales									20.30%	19.10%
Customer Concentration Risk \| Three Largest Customers [Member] \| Sales Revenue, Product Line [Member]
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Percentage change in product sales									56.40%	50.30%	37.00%
Customer Concentration Risk \| Three Largest Customers [Member] \| Sales Revenue, Product Line [Member] \| Minimum
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Percentage change in product sales									10.00%	10.00%	10.80%
Customer Concentration Risk \| Three Largest Customers [Member] \| Sales Revenue, Product Line [Member] \| Maximum
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Percentage change in product sales									16.80%	16.40%	15.00%
Accounting Standards Update 2016-02
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross												$ 472.8
Facility Lease Obligation, Noncurrent												372.2
Right of use operating assets				$ 172.2								326.1
Prepaid Rent												70.8
Operating Lease, Liability												255.3
Retained Earnings
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Adoption of new guidance, value	(90.3)				$ 6.1				$ (90.3)	$ 6.1	$ (18.8)
Net income (loss)									2,404.3	$ 77.6	$ 443.3
Retained Earnings \| Accounting Standards Update 2016-02
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Adoption of new guidance, value												$ (90.3)
Difference between Revenue Guidance in Effect before and after Topic 606 \| Accounting Standards Update 2014-09
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Deferred Revenue													$ 10.4
Retained Earnings (Accumulated Deficit)	10.8								10.8				$ 6.0
Total revenues									5.3
Net income (loss)									4.8
Contract with Customer, Asset, Net	17.9								17.9
Pre-Approval Inventory
Business Overview And Summary Of Significant Accounting Policies [Line Items]
Inventories	$ 60.5								$ 60.5

Business Overview and Summary of Significant Accounting Policies (Inventories) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Business Overview and Summary of Significant Accounting Policies [Abstract]
Inventory, Raw Materials	$ 41.2	$ 31.4
Inventory, Work in Process	180.8	90.4
Inventory, Finished Goods	405.6	350.7
Inventory, Net	$ 627.6	$ 472.5

Business Overview and Summary of Significant Accounting Policies (Receivables and Contract Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Accounts Receivable, Net, Current	$ 1,243.2	$ 922.3
Contract with Customer, Liability, Current	$ 6.8	$ 3.4

Business Overview and Summary of Significant Accounting Policies (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Overview and Summary of Significant Accounting Policies [Abstract]
Net income used for basic calculation	$ 889.0	$ 467.6	$ 459.8	$ 587.9	$ (45.0)	$ 330.9	$ (457.4)	$ 249.1	$ 2,404.3	$ 77.6	$ 443.3
Shares used in computing earnings per common share—basic									223.2	222.7	223.9
Weighted-average effect of dilutive securities:
Stock awards									1.6	1.8	1.5
Shares used in computing earnings per common share—diluted									224.8	224.5	225.4
Earnings per common share
Basic (in dollars per share)	$ 4.02	$ 2.09	$ 2.05	$ 2.63	$ (0.20)	$ 1.48	$ (2.05)	$ 1.12	$ 10.77	$ 0.35	$ 1.98
Diluted (in dollars per share)	$ 4.00	$ 2.08	$ 2.04	$ 2.61	$ (0.20)	$ 1.47	$ (2.05)	$ 1.11	$ 10.70	$ 0.35	$ 1.97
Antidilutive securities excluded from computation of EPS									3.0	2.8	4.0

Acquisitions (Narrative) (Details) $ / shares in Units, $ in Millions		1 Months Ended		3 Months Ended
	May 25, 2018 USD ($)	Oct. 31, 2019 USD ($) $ / shares	Nov. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Apr. 30, 2018 kr / shares
Business Acquisition [Line Items]
Asset Acquisition, Contingent Consideration, Milestone Payments				$ 100.0
Syntimmune, Inc [Member]
Business Acquisition [Line Items]
Upfront payment for acquisition of Syntimmune outstanding shares			$ 400.0
Asset Acquisition, Contingent Consideration, Milestone Payments			800.0
Asset Acquisition, Potential Consideration Transfered, Including Contingent Consideration Milestone Payments			1,200.0
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, In-Process Research And Development			$ 375.2			$ 379.3
Achillion [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 926.0
Business Combination, Consideration Transferred, Per Share \| $ / shares		$ 6.30
In Process Research and Development [Member]
Business Acquisition [Line Items]
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Finite-Lived Intangibles	$ 803.7
Asset Acquisition, Share Price \| kr / shares							kr 232
Asset Acquisition, Potential Payments For Development, Regulatory, Commercial Milestones And Royalties On Sales	19.0
Upfront payment for acquisition of Syntimmune outstanding shares	$ 749.3
In Process Research and Development [Member] \| Syntimmune, Inc [Member]
Business Acquisition [Line Items]
Asset Acquisition, Recognized Benefit From Previously Acquired Research And Development					$ 4.1
Danicopan [Member] \| Achillion [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability, Per Share \| $ / shares		1.00
ACH-5528, Phase 3 [Member] \| Achillion [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability, Per Share \| $ / shares		$ 1.00

Acquisitions (Summary of Total Consideration) (Details) - In Process Research and Development [Member] $ in Millions	May 25, 2018 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Cash paid for acquisition of Wilson Therapeutics outstanding shares	$ 749.3
Transaction costs	15.1
Total consideration	764.4
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Cash And Equivalents	45.1
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Finite-Lived Intangibles	803.7
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Labor And Related Liabilities	(71.4)
Asset Acquisition, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities, Other	$ (13.0)

Acquisitions (Wilson Acquisition) (Details) - In Process Research and Development [Member] $ in Millions	May 25, 2018 USD ($)	Apr. 30, 2018 kr / shares
Research and Development Assets Acquired Other than Through Business Combination [Line Items]
Asset Acquisition, Share Price \| kr / shares		kr 232
Asset Acquisition, Potential Payments For Development, Regulatory, Commercial Milestones And Royalties On Sales \| $	$ 19.0

Acquisitions (Asset Acquisition) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Research and Development Assets Acquired Other than Through Business Combination [Line Items]
Research and Development Asset Acquired Other than Through Business Combination, Written-off	$ (4.1)	$ 1,183.0	$ 0.0

Acquisitions (Syntimmune) (Details) - Syntimmune, Inc [Member] - USD ($) $ in Millions	1 Months Ended
	Nov. 30, 2018	Dec. 31, 2018
Consideration
Upfront payment for acquisition of Syntimmune outstanding shares	$ 400.0
Asset Acquisition, Cash Acquired	4.2
Asset Acquisition, Working Capital Adjustment	2.3
Transaction costs	0.9
Total consideration	407.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Cash	4.2
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, In-Process Research And Development	375.2	$ 379.3
Deferred tax assets	25.1
Other assets and liabilities	2.9
Asset Acquisition, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net Assets	$ 407.4

Property, Plant and Equipment, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Jan. 01, 2019
Property, Plant and Equipment [Line Items]
Land	$ 9.6	$ 9.6
Buildings and improvements	208.7	520.1
Machinery and laboratory equipment	126.0	161.7
Computer hardware and software	155.1	144.8
Furniture and office equipment	23.4	27.5
Construction-in-progress	734.2	827.1
Finance lease, right-of-use asset	127.2	0.0
Property, Plant and Equipment, Gross	1,384.2	1,690.8
Less: Accumulated depreciation and amortization	(220.9)	(219.3)
Property, Plant and Equipment, Net	1,163.3	1,471.5
Depreciation and amortization of property, plant and equipment	376.8	405.3	$ 496.7
Computer software costs	53.4	50.3
Computer software, depreciation and amortization expense	15.3	17.4	16.0
Property, Plant, and Equipment [Member]
Property, Plant and Equipment [Line Items]
Depreciation and amortization of property, plant and equipment	$ 56.8	$ 77.9	$ 95.8
Accounting Standards Update 2016-02
Property, Plant and Equipment [Line Items]
Finance lease, right-of-use asset				$ 83.1
Property, Plant and Equipment, Gross					$ 472.8

Intangible Assets and Goodwill (Schedule of Intangible Assets and Goodwill) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 298.0
Intangible Assets, Cost	4,778.4	$ 4,760.4
Intangible Assets, Accumulated Amortization	1,434.1	1,119.1
Intangible assets, net	3,344.3	3,641.3
Goodwill, Cost	5,040.3	5,040.3
Goodwill, Accumulated Amortization	2.9	2.9
Goodwill	5,037.4	5,037.4
Licensing Agreements
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	57.0	39.0
Finite-lived Intangible Assets, Accumulated Amortization	(34.7)	(29.3)
Finite-lived Intangible Assets, Net	22.3	9.7
Patents [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	10.5	10.5
Finite-lived Intangible Assets, Accumulated Amortization	(10.5)	(10.5)
Finite-lived Intangible Assets, Net	$ 0.0	0.0
Intangible Assets, Estimated Life (months)	7 years
Purchased Technology [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	$ 4,710.5	4,710.5
Finite-lived Intangible Assets, Accumulated Amortization	(1,388.7)	(1,079.1)
Finite-lived Intangible Assets, Net	3,321.8	3,631.4
Other Intangibles [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Cost	0.4	0.4
Finite-lived Intangible Assets, Accumulated Amortization	(0.2)	(0.2)
Finite-lived Intangible Assets, Net	$ 0.2	$ 0.2
Intangible Assets, Estimated Life (months)	5 years
Minimum \| Licensing Agreements
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	3 years
Minimum \| Purchased Technology [Member]
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	6 years
Maximum \| Licensing Agreements
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	8 years
Maximum \| Purchased Technology [Member]
Intangible Assets [Line Items]
Intangible Assets, Estimated Life (months)	16 years
Synageva BioPharma Corp. [Member] \| Purchased Technology [Member]
Intangible Assets [Line Items]
Finite-lived Intangible Assets, Net	$ 2,992.4

Intangible Assets and Goodwill (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangibles Disclosure [Line Items]
Capitalized regulatory approval and commercial milestones	$ 18.0	$ 8.0
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	298.0
Finite-Lived Intangible Assets, Amortization Expense, Year Two	298.0
Finite-Lived Intangible Assets, Amortization Expense, Year Three	298.0
Finite-Lived Intangible Assets, Amortization Expense, Year Four	298.0
Finite-Lived Intangible Assets, Amortization Expense, Year Five	298.0
Impairment of intangible assets	0.0	0.0	$ 31.0
Amortization of Intangible Assets	315.0	321.1	$ 320.2
Purchased Technology [Member]
Goodwill and Intangibles Disclosure [Line Items]
Finite-Lived Intangible Assets, Net	$ 3,321.8	$ 3,631.4

Intangible Assets and Goodwill (Schedule of Changes in the Carrying Amount of Goodwill) (Details) $ in Millions	Dec. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 5,037.4
Goodwill, ending balance	$ 5,037.4

Marketable Securities (Summary of Avaiable-for-sale Securities Held) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 369.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.0
Debt Securities, Available-for-sale	369.0
Available-for-sale securities, amortized cost		$ 225.7
Available-for-sale securities, gross unrealized holding gains		0.0
Available-for-sale debt securities, gross unrealized holding losses		(0.1)
Available-for-sale securities, fair value		225.6
Commercial Paper [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	246.9
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.0
Debt Securities, Available-for-sale	246.9
Available-for-sale securities, amortized cost		52.1
Available-for-sale securities, gross unrealized holding gains		0.0
Available-for-sale debt securities, gross unrealized holding losses		0.0
Available-for-sale securities, fair value		52.1
Corporate Bond Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	24.3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.0
Debt Securities, Available-for-sale	24.3
Available-for-sale securities, amortized cost		122.9
Available-for-sale securities, gross unrealized holding gains		0.0
Available-for-sale debt securities, gross unrealized holding losses		(0.1)
Available-for-sale securities, fair value		122.8
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	70.4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.0
Debt Securities, Available-for-sale	70.4
Available-for-sale securities, amortized cost		17.5
Available-for-sale securities, gross unrealized holding gains		0.0
Available-for-sale debt securities, gross unrealized holding losses		0.0
Available-for-sale securities, fair value		17.5
Certificates of Deposit [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	27.4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0.0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0.0
Debt Securities, Available-for-sale	$ 27.4
Available-for-sale securities, amortized cost		33.2
Available-for-sale securities, gross unrealized holding gains		0.0
Available-for-sale debt securities, gross unrealized holding losses		0.0
Available-for-sale securities, fair value		$ 33.2

Marketable Securities (Available-for-sale Securities by Classification in Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	$ 369.0
Available-for-sale securities, fair value		$ 225.6
Cash and Cash Equivalents [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	328.1
Available-for-sale securities, fair value		43.8
Marketable Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale	$ 40.9
Available-for-sale securities, fair value		$ 181.8

Marketable Securities (Available-for-sale Debt Securities by Contractual Maturity) (Details) $ in Millions	Dec. 31, 2019 USD ($)
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value	$ 365.5
Available-for-sale Securities, Debt Maturities, Year Two Through Three, Fair Value	3.5
Available-for-sale Securities, Debt Maturities, Year Four Through Five, Fair Value	0.0
Debt Securities, Available-for-sale	$ 369.0

Marketable Securities (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Aggregate fair value of available-for-sale debt securities in an unrealized loss position	$ 21.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		$ 128.7
Debt Securities, Trading, and Equity Securities, FV-NI	$ 23.1	$ 16.5

Derivative Instruments and Hedging Activities (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Estimated amount to be reclassified from other comprehenisve income in next year	$ 6.7
Gain in other income and expense	$ (0.4)	$ 23.0	$ (14.7)
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign exchange forward contracts durations (months)	60 months
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Foreign exchange forward contracts durations (months)	8 months
Interest Rate Contract [Member] \| Designated as Hedging Instrument [Member]
Derivative [Line Items]
Estimated amount to be reclassified from other comprehenisve income in next year	$ (19.5)
Foreign Exchange Forward [Member] \| Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional amount of foreign exchange contracts	1,089.9
Foreign Exchange Forward [Member] \| Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional amount of foreign exchange contracts	1,974.6
Foreign Exchange Forward, Open Expense [Member] \| Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional amount of foreign exchange contracts	$ 14.0

Derivative Instruments and Hedging Activities (Schedule of Interest Rate Derivatives) (Details) - Designated as Hedging Instrument [Member] $ in Millions	Dec. 31, 2019 USD ($)
Interest Rate Swap Two [Member]
Derivative [Line Items]
Notional amount of foreign exchange contracts	$ 450.0
Interest Rate Swap Two [Member] \| Minimum
Derivative [Line Items]
Derivative, Fixed Interest Rate	2.60%
Interest Rate Swap Two [Member] \| Maximum
Derivative [Line Items]
Derivative, Fixed Interest Rate	2.79%
Interest Rate Swap Four [Member]
Derivative [Line Items]
Notional amount of foreign exchange contracts	$ 1,300.0
Interest Rate Swap Four [Member] \| Minimum
Derivative [Line Items]
Derivative, Fixed Interest Rate	2.37%
Interest Rate Swap Four [Member] \| Maximum
Derivative [Line Items]
Derivative, Fixed Interest Rate	2.83%

Derivative Instruments and Hedging Activities Schedule of Cash Flow Hedges in AOCI (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Total revenues	$ 1,384.3	$ 1,263.1	$ 1,203.3	$ 1,140.4	$ 1,128.8	$ 1,026.5	$ 1,045.0	$ 930.9	$ 4,991.1	$ 4,131.2	$ 3,551.1
Interest Expense									77.8	98.2	98.4
Product [Member]
Derivative [Line Items]
Total revenues									4,990.0	4,130.1	3,549.5
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member] \| Foreign Exchange Forward [Member]
Derivative [Line Items]
Total revenues									36.8	(1.8)	28.9
Interest Expense									0.0	0.0	0.0
Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member] \| Interest Rate Contract [Member]
Derivative [Line Items]
Total revenues									0.0	0.0	0.0
Interest Expense									$ (13.3)	$ (13.6)	$ 1.8

Derivative Instruments and Hedging Activities (Schedule Of Other Comprehensive Income And Earnings From Foreign Exchange Contracts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Foreign Exchange Contract [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss) recognized in AOCI, net of tax	$ 27.9	$ 37.7	$ (96.1)
Foreign Exchange Contract [Member] \| Net product sales
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss) reclassified from AOCI to net product sales (Effective portion), net of tax	28.4	(1.4)	18.7
Interest Rate Contract [Member] \| Cash Flow Hedging [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (loss) recognized in AOCI, net of tax	(39.0)	(4.8)	7.9
Gain (loss) reclassified from AOCI to net product sales (Effective portion), net of tax	$ 10.2	$ 10.8	$ (1.1)

Derivative Instruments and Hedging Activities (Schedule Of Fair Value Of Outstanding Derivatives) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	$ 30.5	$ 60.9
Liability Derivatives, Fair Value	89.1	40.0
Foreign Exchange Forward [Member] \| Other Current Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	6.2	7.3
Foreign Exchange Forward [Member] \| Other Current Liabilities [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	20.4	11.5
Foreign Exchange Forward [Member] \| Other Non Current Assets \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	0.6	0.3
Foreign Exchange Forward [Member] \| Other Non Current Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	1.1	3.1
Foreign Exchange Forward [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	12.7	16.9
Foreign Exchange Forward [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value	17.2	23.6
Interest Rate Contract [Member] \| Other Current Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	19.5	0.8
Interest Rate Contract [Member] \| Other Non Current Assets \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value		0.0
Interest Rate Contract [Member] \| Other Non Current Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives, Fair Value	$ 41.9	17.3
Interest Rate Contract [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives, Fair Value		$ 20.1

Derivative Instruments and Hedging Activities (Schedule of Offsetting Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Asset Derivatives, Fair Value	$ 30.5	$ 60.9
Derivative Asset, Fair Value, Gross Liability		0.0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	30.5	60.9
Derivative, Collateral, Obligation to Return Securities	(21.4)	(30.2)
Derivative, Collateral, Obligation to Return Cash	0.0	0.0
Derivative Asset, Fair Value, Amount Offset Against Collateral	9.1	30.7
Derivative Liability, Fair Value, Gross Liability	(89.1)	(40.0)
Derivative Liability, Fair Value, Gross Asset		0.0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	89.1	40.0
Derivative, Collateral, Right to Reclaim Securities	21.4	30.2
Derivative, Collateral, Right to Reclaim Cash	0.0	0.0
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 67.7	$ 9.8

Other Investments (Details) - USD ($) $ in Millions		1 Months Ended						3 Months Ended		9 Months Ended	12 Months Ended
Other Investments (Details) - USD ($) $ in Millions	Dec. 09, 2019	Dec. 31, 2019	Oct. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Jan. 31, 2019	Oct. 31, 2018	Dec. 31, 2019	Mar. 31, 2018	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2014
Payments to Acquire Other Investments											$ 73.3	$ 10.3	$ 0.0
Unrealized Gain (Loss) on Investments											26.9	40.2	0.0
Other income and (expense)											35.9	5.5	0.3
Research and Development Expense											886.0	730.4	$ 878.4
Moderna LLC [Member]
Payments to Acquire Other Investments														$ 37.5
Unrealized Gain (Loss) on Investments									$ 100.8		32.8	(56.4)
Payments to Acquire Other Investments												81.9
Proceeds from sale of investment	$ 114.7
Realized gain from sale of investment	$ 77.2
Dicerna [Member]
Unrealized Gain (Loss) on Investments											9.5	1.4
Payments to Acquire Equity Method Investments							$ 10.3
Equity Securities, FV-NI		$ 18.4						$ 18.4			18.4	$ 8.9
Caelum Biosciences [Member]
Payments to Acquire Other Investments											41.0
Option To Acquire Remaining Equity, Amount						$ 16.1					64.0
Other income and (expense)		32.0
Zealand [Member]
Unrealized Gain (Loss) on Investments										$ 14.7
Payments to Acquire Equity Method Investments					$ 13.8
Equity Securities, FV-NI		28.5						28.5			28.5
Eidos [Member] [Member]
Unrealized Gain (Loss) on Investments											7.9
Payments to Acquire Equity Method Investments				$ 19.9
Equity Securities, FV-NI		27.8						27.8			27.8
Stealth [Member]
Unrealized Gain (Loss) on Investments								(5.2)
Payments to Acquire Equity Method Investments			$ 9.6
Equity Securities, FV-NI		$ 4.4						$ 4.4			4.4
Collaborative Arrangement [Member] \| Caelum Biosciences [Member]
Additional upfront funding accrued											20.0
Research and Development Expense											3.1
Collaborative Agreement, Amendment [Member] \| Caelum Biosciences [Member]
Research and Development Expense											$ 4.1

Accounts Payable and Accrued Expenses (Schedule of Accrued Expenses) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accrued Liabilities [Abstract]
Accounts Payable	$ 74.0	$ 74.4
Royalties	20.1	27.0
Payroll and employee benefits	191.3	170.4
Taxes payable	103.9	24.4
Rebates payable	250.1	122.8
Clinical	67.3	58.6
Manufacturing	72.8	72.0
Restructuring Reserve, Current	6.8	4.2
Other	180.4	144.4
Accounts Payable and Accrued Liabilities, Current	$ 966.7	$ 698.2

Debt (Details) - USD ($) $ in Millions		12 Months Ended
Debt (Details) - USD ($) $ in Millions	Jun. 22, 2015	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 07, 2018
Debt Instrument [Line Items]
Amortization of Financing Costs		$ 5.0	$ 8.0	$ 9.2
Debt Issuance Costs, Net		$ 15.8	20.8
Credit Agreement [Member]
Debt Instrument [Line Items]
Payments of Financing Costs			$ 53.1
Senior Secured Term Loan [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate at Period End		3.05%
Line of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Letters of credit, amount outstanding		$ 1.0
Eurodollar [Member] \| Minimum \| Line of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on varaible rate	1.25%
Eurodollar [Member] \| Maximum \| Line of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on varaible rate	2.00%
Base Rate [Member] \| Minimum \| Line of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on varaible rate	0.25%
Base Rate [Member] \| Maximum \| Line of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on varaible rate	1.00%
Revolving Credit Facility [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity					$ 1,000.0
Debt Instrument, Covenant Compliance, Net Debt To EBITDA					3.50
Debt Instrument, Covenant Compliance, EBITDA To Cash Interest Expense, Minimum					3.50
Revolving Credit Facility [Member] \| Line of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Long-term debt		250.0
Senior Secured Term Loan [Member] \| Line of Credit [Member] \| Credit Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, principal amount					$ 2,612.5
Debt Instrument, Quarterly Payment, Percentage of Total Borrowings					5.00%
Principal payments		(98.0)
Long-term debt		$ 2,514.5

Debt - Schedule of Maturities of Long-term Debt (Details) $ in Millions	Dec. 31, 2019 USD ($)
Debt Disclosure [Abstract]
2020	$ 130.6
2021	130.6
2022	130.6
2023	2,122.7
2024	$ 0.0

Leases - Lease Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Finance lease, right-of-use asset	$ 127.2	$ 0.0
Right of use operating assets	204.0	0.0
Noncurrent operating lease liabilities	164.1	$ 0.0
Right Of Use Operating Assets [Member]
Lessee, Lease, Description [Line Items]
Finance lease, right-of-use asset	0.0
Right of use operating assets	204.0
Property, Plant and Equipment [Member]
Lessee, Lease, Description [Line Items]
Finance lease, right-of-use asset	116.3
Right of use operating assets	0.0
Other Current Assets [Member]
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Current	5.2
Operating Lease, Liability, Current	18.8
Right Of Use Operating Liabilities [Member]
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Noncurrent	0.0
Noncurrent operating lease liabilities	164.1
Other Liabilities
Lessee, Lease, Description [Line Items]
Finance Lease, Liability, Noncurrent	72.9
Noncurrent operating lease liabilities	$ 0.0

Leases - Lease Cost (Details) $ in Millions	12 Months Ended
Leases - Lease Cost (Details) $ in Millions	Dec. 31, 2019 USD ($)
Leases [Abstract]
Financing Lease Cost	$ 14.8
Amortization of ROU Assets	10.9
Interest on Lease Liabilities	3.9
Operating Lease Cost	34.3
Variable Lease Cost	11.8
Total Lease Cost	$ 60.9

Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Leases - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Operating Leased Assets [Line Items]
Lease cost	$ 60.9
Lessee, Operating Lease, Liability, Payments, Due	223.6
Lonza Group AG [Member]
Operating Leased Assets [Line Items]
Other Commitment		$ 1,084.6
Lessee, Operating Lease, Liability, Payments, Due		$ 88.7
Inventory [Member]
Operating Leased Assets [Line Items]
Lease cost	$ 15.6

Leases - Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Cash Paid For Amounts Included In Measurement of Liabilities	$ 32.3
Operating Cash Flows From Financing Leases	3.9
Operating Cash Flows From Operating Leases	23.5
Financing Cash Flows From Financing Leases	4.9
ROU Assets Obtained In Exchange For New Financing Liabilities	0.0
ROU Asset Obtained In Exchange for New Operating Liabilities	27.5	$ 0.0	$ 0.0
Right-of-Use Asset Obtained in Exchange for Finance Lease Rent Prepayment	44.2
Finance lease, right-of-use asset	127.2	0.0
Right-of-Use Asset Obtained in Exchange for Operating Lease, Rent Prepayments	26.6
Right of use operating assets	$ 204.0	$ 0.0
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Finance lease, right-of-use asset				$ 83.1
Right of use operating assets				$ 172.2	$ 326.1

Leases - Lease Maturity (Details) $ in Millions	Dec. 31, 2019 USD ($)
Financing
2020	$ 8.8
2021	9.0
2022	9.2
2023	9.2
2024	9.4
Thereafter	54.6
Operating
2020	25.7
2021	23.0
2022	21.6
2023	20.9
2024	20.3
Thereafter	112.1
Total
2020	34.5
2021	32.0
2022	30.8
2023	30.1
2024	29.7
Thereafter	$ 166.7

Leases - Lease Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Finance Lease, Weighted Average Remaining Lease Term	10 years 8 months 1 day
Operating Lease, Weighted Average Remaining Lease Term	10 years 2 months 1 day
Lease, Weighted Average Remaining Lease Term	10 years 3 months 25 days
Finance Lease, Weighted Average Discount Rate, Percent	4.85%
Operating Lease, Weighted Average Discount Rate, Percent	4.10%
Lease, Weighted Average Discount Rate	4.33%
Finance Lease, Liability, Payments, Due	$ 100.2
Lessee, Operating Lease, Liability, Payments, Due	223.6
Lessee, Lease Liability, Payments, Due	323.8
Finance Lease, Liability, Undiscounted Excess Amount	22.1
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	40.7
Lessee, Lease Liability, Undiscounted Excess Amount	62.8
Finance Lease, Liability	78.1
Operating Lease, Liability	182.9
Lessee, Lease Liability	$ 261.0

Leases - Aggregate Future Minimum Non-cancellable Commitments Under Leases (Details) $ in Millions	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 27.8
2020	24.7
2021	21.3
2022	19.9
2023	19.7
Thereafter	$ 132.2

Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended						3 Months Ended					9 Months Ended	12 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Jan. 31, 2019	Nov. 30, 2018	Oct. 31, 2018	Dec. 31, 2019	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019
Commitments and Contingencies [Line Items]
Research and Development Expense													$ 886.0	$ 730.4	$ 878.4
Asset Acquisition, Contingent Consideration, Milestone Payments								$ 100.0
Other Commitment, potential payment							$ 60.6						60.6
Lonza Agreement [Member]
Commitments and Contingencies [Line Items]
Remaining total commitments with Lonza							1,099.9						1,099.9
CANADA
Commitments and Contingencies [Line Items]
Increase (Decrease) In Revenue From Contract With Customer, Excluding Assessed Tax													(29.8)
DOJ And OIG
Commitments and Contingencies [Line Items]
Loss Contingency Accrual, Payments													13.1
Canadian Patented Medicine Prices Review Board
Commitments and Contingencies [Line Items]
Escrow Deposit							43.4						43.4
Lonza Group AG [Member]
Commitments and Contingencies [Line Items]
Unrecorded Unconditional Purchase Obligation, Undiscounted Fixed Payment Amount							100.0						100.0
Collaborative Arrangement [Member] \| Caelum Biosciences [Member]
Commitments and Contingencies [Line Items]
Collaboration Agreement, Upfront Payment				$ 30.0
Derivative Liability							24.0						24.0			$ 27.1
Additional upfront funding accrued													20.0
Additional equity interest funding													60.0
Collaboration Agreement, Potential Future Payments, Acquisition Option Exercise				500.0
Research and Development Expense													3.1
Collaboration Agreement, Potential Future Payments, Milestone Achievement				30.0
Zealand Pharma [Member] \| Zealand [Member]
Commitments and Contingencies [Line Items]
Collaboration Agreement, Potential Future Payments, Option Fee												$ 15.0
Payments To Acquire Licenses And Equity Investment			$ 40.0
Prepaid Research And Development Expense		$ 5.0						5.0				5.0
Research and Development Expense									$ 21.2
Collaboration Agreement, Potential Future Payments, Milestone Achievement												610.0
Collaboration Agreement, Potential Future Payments, Additional Milestone Achievement												115.0
Collaboration and License Agreement [Member]
Commitments and Contingencies [Line Items]
Collaboration Agreement, Potential Future Payments, Milestone Achievement													54.0
Affibody AB [Member] \| Affibody [Member]
Commitments and Contingencies [Line Items]
Payments To Acquire Licenses And Equity Investment			25.0
Collaboration Agreement, Potential Future Payments, Milestone Achievement												$ 625.0
Eidos [Member] [Member] \| Eidos [Member] [Member]
Commitments and Contingencies [Line Items]
Payments To Acquire Licenses And Equity Investment		50.0
Research and Development Expense								$ 30.1
Collaboration Agreement, Potential Future Payments, Milestone Achievement													30.0
Dicerna Pharmaceutical Collaboration Agreement [Member] \| Dicerna [Member]
Commitments and Contingencies [Line Items]
Payments To Acquire Licenses And Equity Investment						$ 37.0
Research and Development Expense							20.0			$ 26.7
Research and Development Arrangement, Potential Payment, Maximum							629.1						629.1
License Agreement 1 [Member] \| Halozyme Therapeutics, Inc [Member]
Commitments and Contingencies [Line Items]
Research and Development Arrangement, Potential Payment, Maximum							160.0						$ 160.0
Research and Development Expense (Excluding Acquired in Process Cost)											$ 40.0
Caelum Biosciences [Member] \| Collaborative Arrangement [Member]
Commitments and Contingencies [Line Items]
Equity Method Investment, Aggregate Cost				$ 57.1
Zealand [Member]
Commitments and Contingencies [Line Items]
Payments to Acquire Equity Method Investments			$ 13.8
Eidos [Member] [Member]
Commitments and Contingencies [Line Items]
Payments to Acquire Equity Method Investments		$ 19.9
Stealth [Member]
Commitments and Contingencies [Line Items]
Payments To Acquire Licenses And Equity Investment	$ 30.0
Payments to Acquire Equity Method Investments	$ 9.6
Stealth [Member] \| Option Agreement [Member]
Commitments and Contingencies [Line Items]
Research and Development Expense							$ 20.4
Dicerna [Member]
Commitments and Contingencies [Line Items]
Payments to Acquire Equity Method Investments						$ 10.3
Syntimmune, Inc [Member]
Commitments and Contingencies [Line Items]
Asset Acquisition, Contingent Consideration, Milestone Payments					$ 800.0

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Current Foreign Tax Expense (Benefit)			$ 158.2	$ 74.7	$ 107.5
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount			$ 196.1	$ 54.2	$ 33.2
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Percent			0.10%	1.60%	3.90%
Foreign Earnings Repatriated			$ 187.6	$ 206.1	$ 171.7
Repatriation of foreign earnings, amount			$ 269.5	$ 108.7	$ 35.4
Foreign-derived intangible income			12.40%	44.80%	6.50%
Deferred Income Tax Expense (Benefit)			$ (455.5)	$ 32.9	$ (45.9)
Income tax expense			$ 225.5	(164.6)	(104.5)
Effective Income Tax Rate Reconciliation, Deduction, Percent			0.80%
Income Tax Benefit, Foreign-Derived Intangible Income			$ 17.0
Tax Cuts and Jobs Act of 2017, income tax benefit, foreign tax credits				$ 67.7	171.1
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Provisional Income Tax Benefit, Foreign, Percent				28.00%
Tax Cuts and Jobs Act of 2017, transition tax, Income expense					177.9
Tax Cut and Jobs Act of 2017, global intangible low-taxed income minimum tax, income tax expense					$ 165.4
Effective Income Tax Rate Reconciliation, Tax Cuts And Jobs Act Of 2017, Change In Income Tax Rate, Percent					62.70%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Amount				$ 21.1
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-based Compensation Cost, Percent				8.70%
Tax Cuts and Jobs Act of 2017, Transition tax, Income expense, percent					32.50%
Decrease effective tax rate					3.60%
Effective income tax rate reconciliation, Tax Cuts and Jobs Act of 2017, amount				$ (56.5)	$ 45.8
Effective income tax rate reconciliation, Tax Cuts and Jobs Act of 2017, percent					0.084
Tax Cuts and Jobs Act of 2017, transition tax, foreign income subject to domestic taxation					$ 195.6
Tax Cuts and Jobs Act of 2017, transition tax, foreign tax credit					17.7
Tax Cuts and Jobs Act of 2017, deferred tax asset, income tax expense, amount					$ 292.4
Other permanent differences			0.00%	0.00%	53.40%
Tax Cuts and Jobs Act of 2017, income tax expense, amount, foreign income subject to domestic taxation					$ 121.3
Tax Cuts and Jobs Act of 2017, income tax expense, amount, foreign income subject to domestic taxation, percent					(22.20%)
Tax Cuts and Jobs Act of 2017, income tax benefit, foreign tax credits, percent					(31.20%)
Tax Cuts and Jobs Act of 2017, deferred tax liability, income tax benefit					$ (5.1)
Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Change In Tax Rate, Provisional Income Tax Expense (Benefit), Permanent Differences, Percentage					0.90%
Effective Income Tax Rate Reconciliation, Tax Cut And Jobs Act 2017, Global Intangible Low-Taxed Income Minimum Tax, Percent					30.20%
Tax Cut and Jobs Act of 2017, global intangible low-taxed income minimum tax, income tax expense, deferred tax expense				$ 67.7	$ 236.9
Tax Cut and Jobs Act of 2017, global intangible low-taxed income minimum tax, income tax benefit, unrecognized tax benefit					71.5
Tax Cuts and Jobs Act of 2017, transition tax, estimated tax credits					28.0
Tax Cuts and Jobs Act of 2017, estimated deferred tax liabilities, foreign				11.1	533.4
Effective Income Tax Rate Reconciliation, Tax Cuts and Jobs Act of 2017, Transition Tax on Accumulated Foreign Earnings, Amount			$ (1,408.2)
Change in unrecognized tax benefits			$ 4.6	35.4	27.1
Statute of limitations, minimum (years)			3 years
Statute of limitations, maximum (years)			6 years
Federal [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 12.5		$ 12.5
Income tax credit carryforwards	280.5		280.5
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Current Foreign Tax Expense (Benefit)			193.2	58.1	54.4
Tax Cuts and Jobs Act of 2017, deferred tax asset, income tax expense, amount					2.9
Tax Cuts and Jobs Act of 2017, deferred tax liability, estimated increase in income tax payable					2.2
Tax Cuts and Jobs Act of 2017, deferred tax asset, estimated increase in deferred taxes					$ 0.7
Net operating loss carryforwards	43.7		43.7
Income tax credit carryforwards	67.3		67.3
Tax credit carryforwards, subject to expiration	47.2		47.2
Tax credit carryforwards, not subject to expiration	20.1		20.1
In Process Research and Development [Member] \| Wilson Therapeutics And Syntimmune [Member]
Income Tax Contingency [Line Items]
Income tax expense				$ (248.4)
In Process Research and Development [Member] \| Wilson Therapeutics [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount				69.70%
In Process Research and Development [Member] \| Syntimmune, Inc [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount				32.90%
Intellectual Property Election [Member] \| Wilson Therapeutics [Member]
Income Tax Contingency [Line Items]
Deferred Income Tax Expense (Benefit)		$ (95.7)	(95.7)
Valuation Allowance Release [Member]
Income Tax Contingency [Line Items]
Deferred Income Tax Expense (Benefit)		$ (30.3)	(30.3)
Wilson Therapeutics [Member]
Income Tax Contingency [Line Items]
Income tax expense			(10.2)
Subsidiaries [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	$ 1,839.3
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Percent	17.50%
Subsidiaries [Member] \| Intellectual Property Election [Member]
Income Tax Contingency [Line Items]
Deferred Income Tax Expense (Benefit)	$ (2,221.5)
Connecticut \| State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards	27.3		27.3
Income tax credit carryforwards	$ 39.7		$ 39.7

Income Taxes (Schedule of Income Tax Provision (Benefit) on Income Before Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S.	$ 2.0	$ (451.4)	$ (43.9)
Non-U.S.	2,176.8	693.6	591.7
Income before income taxes	$ 2,178.8	$ 242.2	$ 547.8

Income Taxes (Schedule of Components of Income Tax Provision (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Domestic
Current	$ 71.8	$ 57.0	$ 42.9
Deferred	1,731.0	49.5	7.2
Total Domestic	1,802.8	106.5	50.1
Foreign
Current	158.2	74.7	107.5
Deferred	(2,186.5)	(16.6)	(53.1)
Total Foreign	(2,028.3)	58.1	54.4
Total
Current	230.0	131.7	150.4
Deferred	(455.5)	32.9	(45.9)
Income Tax Expense (Benefit)	$ (225.5)	$ 164.6	$ 104.5

Income Taxes (Reconciliation of the Statutory U.S. Federal Income Tax Rate to Effective Income Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
U.S. federal statutory tax rate	21.00%	21.00%	35.00%
Benefit of foreign earnings	(12.60%)	(71.20%)	60.10%
Tax credits	(0.70%)	(17.00%)	(10.70%)
Tax reserves	(0.10%)	12.10%	(14.00%)
Re-measurement of deferred taxes as a result of the Tax Act	0.00%	0.00%	(53.40%)
Acquired in-process research & development	0.00%	102.60%	0.00%
Intra-entity asset transfer of intellectual property	(17.50%)	0.00%	0.00%
Foreign-derived intangible income	(1.60%)	(4.50%)	0.00%
U.S. state taxes	0.70%	14.20%	1.50%
Other permanent differences	0.50%	10.80%	0.60%
Effective Income Tax Rate	(10.30%)	68.00%	19.10%

Income Taxes (Schedule of Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating losses	$ 102.9	$ 41.8
Income tax credits	328.1	371.6
Stock compensation	57.1	47.6
Accruals and allowances	65.2	105.8
Unrealized losses	18.8	0.0
Research and development expenses	3.5	5.2
Accrued royalties	0.8	89.1
ROU leases	46.2	0.0
Intangible assets	1,967.3	0.0
Gross deferred tax assets	2,589.9	661.1
Valuation allowance	(72.6)	(19.6)
Total deferred tax assets	2,517.3	641.5
Deferred tax liabilities:
Depreciable assets	(5.1)	(88.7)
Unrealized gains	0.0	(6.6)
Investment in foreign partnership	(2,249.5)	(566.6)
ROU leases	(53.9)	0.0
Intangible liabilities	0.0	(268.8)
Total deferred tax liabilities	(2,308.5)	(930.7)
Net deferred tax (liability) asset	$ 208.8
Net deferred tax (liability) asset		$ (289.2)

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning of period balance	$ 92.7	$ 60.9	$ 138.9
Increases for tax positions taken during a prior period	3.4	9.1	5.6
Decreases for tax positions taken during a prior period	(4.9)	(5.8)	(85.8)
Increases for tax positions taken during the current period	43.8	28.8	19.3
Decreases for tax positions related to settlements	0.0	0.0	(15.8)
Decreases for tax positions related to lapse of statute	(1.2)	(0.3)	(1.3)
End of period balance	$ 133.8	$ 92.7	$ 60.9

Share-based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum contractual term under all plans (in years)	10
Total compensation cost not yet recognized on non-vested awards	$ 351.4
Period for rececognition for compensation cost not yet recognized of non-vested awards	1 year 8 months 15 days
Total intrinsic value of stock options exercised	$ 14.7	$ 27.5	$ 88.9
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 10.1	27.2	$ 61.5
Weighted average fair value at the date of grant for options granted			$ 42.59
Restricted Stock, Grants in Period	2,400,000
Restricted Stock, Grants in Period, Weighted Average Grant Date Fair Value	$ 133.89
Allocated Share-based Compensation Expense	$ 237.0	$ 203.0	$ 243.1
Purchase per share of fair market value of common stock (percent) (lower of)	85.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General vesting period (in years)	4 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General vesting period (in years)	4 years
Restricted Stock, Grants in Period, Weighted Average Grant Date Fair Value	$ 133.89	$ 119.27	$ 125.39
Restricted Stock, Vested in Period, Weighted Average Grant Date Fair Value	$ 161.3	$ 181.7	$ 157.0
Performance-based Restricted Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General vesting period (in years)	3 years
Market-Based Performance [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$ 46.3	14.9
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares authorized	1,000,000.0
Inventory [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	$ 12.9	$ 14.5	$ 15.4
Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock, Grants in Period	400,000
Senior Management [Member] \| Market-Based Performance [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock, Grants in Period, Weighted Average Grant Date Fair Value	$ 147.79
2017 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares authorized	18,200,000

Share-based Compensation (Schedule of Components of Allocated Share-Based Compensation Expense and Capitalization of Share Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Period for rececognition for compensation cost not yet recognized of non-vested awards	1 year 8 months 15 days
Total share-based compensation expense	$ 237.0	$ 203.0	$ 243.1
Income tax effect	(55.0)	(46.5)	(89.3)
Total share-based compensation expense, net of tax	182.0	156.5	153.8
Cost of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	14.1	16.0	11.1
Research and Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	61.8	57.5	76.4
Selling, General and Administrative Expenses [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total share-based compensation expense	$ 161.1	$ 129.5	$ 155.6

Share-based Compensation (Schedule of Status of Stock Option Plans) (Details) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at beginning of period, Number of shares \| shares	3.6
Outstanding at beginning of period, Weighted Average Exercise Price \| $ / shares	$ 119.68
Granted, Number of shares \| shares	0.0
Granted, Weighted Average Exercise Price \| $ / shares	$ 0
Exercised, Number of shares \| shares	(0.3)
Exercised, Weighted Average Exercise Price \| $ / shares	$ 67.87
Forfeited and cancelled, Number of shares \| shares	(0.3)
Forfeited and cancelled, Weighted Average Exercise Price \| $ / shares	$ 158.71
Outstanding at end of period, Number of shares \| shares	3.0
Outstanding at end of period, Weighted Average Exercise Price \| $ / shares	$ 119.51
Outstanding at end of period, Weighted Average Remaining Contractual Term (in years)	4 years 29 days
Outstanding at end of period, Aggregate Intrinsic Value \| $	$ 49.0
Vested and unvested expected to vest at end of period, Number of shares \| shares	3.0
Vested and unvested expected to vest at end of period, Weighted Average Exercise Price \| $ / shares	$ 119.49
Vested and unvested expected to vest at end of period, Weighted Average Remaining Contractual Term (in years)	4 years 25 days
Vested and unvested expected to vest at end of period, Aggregate Intrinsic Value \| $	$ 49.0
Exercisable at end of period, Number of shares \| shares	2.9
Exercisable at end of period, Weighted Average Exercise Price \| $ / shares	$ 119.15
Exercisable at end of period, Weighted Average Remaining Contractual Term (in years)	3 years 11 months 4 days
Exercisable at end of period, Aggregate Intrinsic Value \| $	$ 48.9

Share-based Compensation (Schedule of Ranges of Weighted Average Assumptions) (Details)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Interest rate, minimum	1.64%
Interest rate, maximum	1.92%
Volatility, minimum	38.78%
Volatility, maximum	39.01%
Dividend yield	0.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years, minimum	4 years 25 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life in years, minimum	4 years 3 months 14 days

Share-based Compensation (Schedule of Status of Non-Vested Restricted Stock) (Details) shares in Millions	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested [Roll Forward]
Nonvested restricted stock, beginning of period \| shares	3.7
Shares issued \| shares	2.4
Shares cancelled \| shares	0.5
Shares vesting \| shares	1.3
Nonvested restricted stock, end of period \| shares	4.3
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average grant date fair value \| $ / shares	$ 123.25
Restricted Stock, Grants in Period, Weighted Average Grant Date Fair Value \| $ / shares	133.89
Cancelled, Weighted average grant date fair value \| $ / shares	126.76
Vested, Weighted average grant date fair value \| $ / shares	125.02
Weighted average grant date fair value \| $ / shares	$ 128.24

Stockholders' Equity (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 03, 2020	Oct. 22, 2019	Feb. 13, 2017
Class of Stock [Line Items]
Repurchase of common stock		$ 416.0	$ 85.0	$ 463.6
Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount						$ 1,000.0	$ 1,000.0
Repurchase of common stock, shares		3.8	0.7
Subsequent Event [Member]
Class of Stock [Line Items]
Repurchase of common stock	$ 1.6
Subsequent Event [Member] \| Common Stock [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount					$ 1,033.9
Common Stock [Member]
Class of Stock [Line Items]
Repurchase of common stock, shares			0.0

Other Comprehensive Income and Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	$ (9.7)	$ (34.4)	$ 60.5
Other Comprehensive Income before Reclassifications	(18.5)	34.0	(79.5)
Amounts reclassified from other comprehensive income	(38.6)	(9.3)	(15.4)
Other comprehensive income (loss), net of tax	(57.1)	24.7	(94.9)
Accumulated comprehensive income (loss), Ending balance	(66.8)	(9.7)	(34.4)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	(2.6)	(4.8)	(6.7)
Other Comprehensive Income before Reclassifications	(6.6)	1.5	0.5
Amounts reclassified from other comprehensive income	0.0	0.7	1.4
Other comprehensive income (loss), net of tax	(6.6)	2.2	1.9
Accumulated comprehensive income (loss), Ending balance	(9.2)	(2.6)	(4.8)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	(0.3)	0.2	(0.4)
Other Comprehensive Income before Reclassifications	0.2	0.1	(0.2)
Amounts reclassified from other comprehensive income	0.0	(0.6)	0.8
Other comprehensive income (loss), net of tax	0.2	(0.5)	0.6
Accumulated comprehensive income (loss), Ending balance	(0.1)	(0.3)	0.2
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	9.6	(13.9)	91.9
Other Comprehensive Income before Reclassifications	(11.1)	32.9	(88.2)
Amounts reclassified from other comprehensive income	(38.6)	(9.4)	(17.6)
Other comprehensive income (loss), net of tax	(49.7)	23.5	(105.8)
Accumulated comprehensive income (loss), Ending balance	(40.1)	9.6	(13.9)
Accumulated Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated comprehensive income (loss), Beginning balance	(16.4)	(15.9)	(24.3)
Other Comprehensive Income before Reclassifications	(1.0)	(0.5)	8.4
Amounts reclassified from other comprehensive income	0.0	0.0	0.0
Other comprehensive income (loss), net of tax	(1.0)	(0.5)	8.4
Accumulated comprehensive income (loss), Ending balance	$ (17.4)	$ (16.4)	$ (15.9)

Other Comprehensive Income and Accumulated Other Comprehensive Income (Reclassifications out of Accumulated Other Comprehensive Income) (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Total revenues

$ 1,384.3

$ 1,263.1

$ 1,203.3

$ 1,140.4

$ 1,128.8

$ 1,026.5

$ 1,045.0

$ 930.9

$ 4,991.1

$ 4,131.2

$ 3,551.1

Other income and (expense)

2.1

(4.8)

9.4

Interest expense

(77.8)

(98.2)

(98.4)

Income before income taxes

2,178.8

242.2

547.8

Income tax expense

225.5

(164.6)

(104.5)

Net income

$ 889.0

$ 467.6

$ 459.8

$ 587.9

$ (45.0)

$ 330.9

$ (457.4)

$ 249.1

2,404.3

77.6

443.3

Reclassification from accumulated other comprehensive income, net

38.6

9.3

15.4

Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Reclassification from accumulated other comprehensive income, net

38.6

9.4

17.6

Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Defined Benefit Pension Items

^[1]

0.0

(0.3)

(0.4)

Accumulated Defined Benefit Plans Adjustment, Net Curtailment Attributable to Parent [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Defined Benefit Pension Items

^[1]

0.0

(0.6)

(1.8)

Accumulated Net Unrealized Investment Gain (Loss) [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Reclassification from accumulated other comprehensive income, net

0.0

0.6

(0.8)

Accumulated Defined Benefit Plans Adjustment [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Defined Benefit Pension Items

0.0

(0.9)

(2.2)

Income tax expense

0.0

(0.2)

(0.8)

Reclassification from accumulated other comprehensive income, net

0.0

(0.7)

(1.4)

Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Income before income taxes

50.1

11.8

27.1

Income tax expense

(11.5)

(2.4)

(9.5)

Net income

38.6

9.4

17.6

Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest Rate Contract [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Interest expense

13.3

13.6

(1.8)

Net product sales

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Total revenues

4,990.0

4,130.1

3,549.5

Net product sales | Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign Exchange Contract [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]

Reclassification out of Accumulated Other Comprehensive Income [Line Items]

Total revenues

$ 36.8

$ (1.8)

$ 28.9

[1]	This AOCI component is included in the computation of net periodic pension benefit cost see Note 17, Employee Benefit Plans, for additional details.

Fair Value Measurement (Schedule Of Acquisition-Related Contingent Consideration) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration arrangements, range of outcomes, value, high			$ 602.0
Asset Acquisition, Contingent Consideration, Milestone Payments		$ 100.0
Contingent consideration			192.4	$ 183.2
Acquisition-Related Contingent Consideration [Roll Forward]
Milestone payments			0.0	0.0	$ (7.0)
Research and Development Expense			886.0	730.4	$ 878.4
Acquisition Related Contingent Consideration [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Contingent consideration			192.4
Acquisition Related Contingent Consideration [Member] \| Level 3 [Member]
Acquisition-Related Contingent Consideration [Roll Forward]
Balance at beginning of period	$ 280.8		280.8
Milestone payments			(100.0)
Changes in fair value			11.6
Balance at end of period			$ 192.4	$ 280.8
Acquisition Related Contingent Consideration [Member] \| Minimum \| Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Inputs, Cost of Debt			3.90%
Fair Value Inputs, Weighted Average Cost of Capital			9.00%
Acquisition Related Contingent Consideration [Member] \| Maximum \| Level 3 [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Inputs, Cost of Debt			5.10%
Fair Value Inputs, Weighted Average Cost of Capital			10.00%
Caelum Biosciences [Member] \| Collaborative Arrangement [Member]
Acquisition-Related Contingent Consideration [Roll Forward]
Collaboration Agreement, Upfront Payment	30.0
Collaboration Agreement, Potential Future Payments, Milestone Achievement	$ 30.0
Derivative Liability			$ 24.0			$ 27.1
Discounted cost of debt			2.10%
Additional upfront funding accrued			$ 20.0
Additional equity interest funding			60.0
Research and Development Expense			3.1
Caelum Biosciences [Member] \| Collaborative Arrangement [Member] \| Minimum
Acquisition-Related Contingent Consideration [Roll Forward]
Discounted cost of debt	3.30%
Caelum Biosciences [Member] \| Collaborative Arrangement [Member] \| Maximum
Acquisition-Related Contingent Consideration [Roll Forward]
Discounted cost of debt	3.50%
Caelum Biosciences [Member] \| Collaborative Agreement, Amendment [Member]
Acquisition-Related Contingent Consideration [Roll Forward]
Research and Development Expense			$ 4.1

Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
Employee Benefit Plans (Narrative) (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Deferred Compensation Arrangement with Individual, Voluntary Deferrals, Percent of Employees' Gross Pay, Maximum	80.00%
Deferred Compensation Arrangement with Individual, Employer Matching Contribution, Percent of Match	6.00%
Amount of each dollar matching contributed up to first six percent of individual base salary and incentive cash bonus	$ 1.00
Percentage of contribution of individual's base salary and incentive cash bonus	6.00%
Defined benefit plan, contributions by employer	$ 18,900,000	$ 14,100,000	$ 15,900,000
Additional minimum liability recorded in other non-current liabiliites	27,700,000
Additional minimum liability charged against other comprehensive income	9,200,000
Estimated future employer contributions in next fiscal year	2,600,000
Other Liabilities
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation liability	$ 23,100,000	$ 16,500,000

Employee Benefit Plans (Schedule of Change in Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation, beginning of year	$ 39.4	$ 43.4
Service cost	6.0	6.3	$ 7.8
Curtailment	0.0	3.8
Other	9.6	(6.5)
Projected benefit obligation, end of year	55.0	39.4	$ 43.4
Accumulated benefit obligation, end of year	$ 49.9	$ 36.1

Employee Benefit Plans (Schedule of Change in Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Change in plan assets:
Fair value of plan assets, beginning of year	$ 21.8	$ 24.2
Employer contributions	3.4	3.0
Plan participants' contributions	1.4	1.3
Curtailment	0.0	(2.4)
Other	0.7	(4.3)
Fair value of plan assets, end of year	27.3	21.8
Funded status at end of year	$ (27.7)	$ (17.6)

Employee Benefit Plans (Schedule of Weighted Average Assumptions Used to Calculate Net Periodic Benefit Cost and the Actuarial Present Value of Projected Benefit Obligations) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Weighted average assumptions - Net Periodic Benefit Cost:
Discount rate	0.80%	0.80%
Long term rate of return on assets	2.50%	2.50%
Rate of compensation increase	1.30%	1.30%
Weighted average assumptions - Projected Benefit Obligation:
Discount Rate	0.10%	0.80%
Rate of compensation increase	0.80%	1.30%

Employee Benefit Plans (Schedule of Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Service cost	$ 6.0	$ 6.3	$ 7.8
Employee contributions	(1.4)	(1.3)	(1.5)
Amortization of prior service costs	(0.2)	(0.3)	(0.4)
Curtailment	0.0	(0.8)	(1.1)
Amortization and deferral of actuarial gain	0.2	0.5	0.8
Other	(0.2)	(0.3)	(0.6)
Total net periodic benefit cost	$ 4.4	$ 4.1	$ 5.0

Employee Benefit Plans (Schedule of Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income [Roll Forward]
Amount included in AOCI - Beginning of year	$ (2.6)	$ (4.8)
Prior service cost	(0.2)	(0.3)
Amortization of net gain (loss)	0.2	0.6
Change in assumptions		0.6
Taxes	2.1	(0.7)
Other	(2.3)	2.0
Change in assumptions	(6.4)
Amount included in AOCI - End of year	$ (9.2)	$ (2.6)

Employee Benefit Plans (Schedule of Estimated Future Benefit Payments) (Details) $ in Millions	Dec. 31, 2019 USD ($)
Retirement Benefits [Abstract]
2020	$ 1.9
2021	1.8
2022	1.9
2023	1.8
2024	1.9
2025 to 2029	$ 9.8

Restructuring and Related Expenses (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Current	$ 6.8				$ 4.2				$ 6.8	$ 4.2
Restructuring expenses									12.0	50.7	$ 286.5
Total revenues	$ 1,384.3	$ 1,263.1	$ 1,203.3	$ 1,140.4	$ 1,128.8	$ 1,026.5	$ 1,045.0	$ 930.9	4,991.1	4,131.2	3,551.1
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring expenses									$ 8.4	$ 4.6	$ 87.3

Restructuring and Related Expenses - Reconciliation of Restructuring Reserve (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Liability, beginning of period	$ 4.2	$ 58.2
Charges	17.2	52.2
Cash settlements	(9.4)	(79.4)
Adjustments to previous estimates	(5.2)	(1.5)
Non Cash Activity	0.0	(25.3)
Liability, end of period	6.8	4.2	$ 58.2
Restructuring Reserve, Current	6.8	4.2
Restructuring expenses	12.0	50.7	286.5
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Liability, beginning of period	4.2	53.8
Charges	14.2	5.8
Cash settlements	(9.3)	(54.2)
Adjustments to previous estimates	(5.8)	(1.2)
Non Cash Activity	0.0	0.0
Liability, end of period	3.3	4.2	53.8
Restructuring expenses	8.4	4.6	87.3
Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Liability, beginning of period	0.0	4.4
Charges	3.0	21.1
Cash settlements	(0.1)	(25.2)
Adjustments to previous estimates	0.6	(0.3)
Non Cash Activity	0.0	0.0
Liability, end of period	3.5	0.0	4.4
Restructuring expenses	3.6	20.8	19.9
Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Liability, beginning of period	0.0	0.0
Charges	0.0	25.3
Cash settlements	0.0	0.0
Adjustments to previous estimates	0.0	0.0
Non Cash Activity	0.0	(25.3)
Liability, end of period	0.0	0.0	0.0
Restructuring expenses	0.0	25.3	179.3
Cost of Sales [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	5.8	152.1
Cost of Sales [Member] \| Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Cost of Sales [Member] \| Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Cost of Sales [Member] \| Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	5.8	152.1
Research and Development Expense [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.1	16.3
Research and Development Expense [Member] \| Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Research and Development Expense [Member] \| Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Research and Development Expense [Member] \| Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.1	16.3
Selling, General and Administrative Expenses [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	19.4	10.9
Selling, General and Administrative Expenses [Member] \| Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Selling, General and Administrative Expenses [Member] \| Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Selling, General and Administrative Expenses [Member] \| Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	19.4	10.9
Restructuring Expense [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	12.0	25.5	104.6
Restructuring Expense [Member] \| Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	8.4	4.6	87.3
Restructuring Expense [Member] \| Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	3.6	20.9	17.3
Restructuring Expense [Member] \| Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Other Income [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	(0.1)	2.6
Other Income [Member] \| Employee Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	0.0	0.0
Other Income [Member] \| Other Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	0.0	(0.1)	2.6
Other Income [Member] \| Facility Closing [Member]
Restructuring Reserve [Roll Forward]
Restructuring expenses	$ 0.0	$ 0.0	$ 0.0

Segment Information - Net Product Sales (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from External Customer [Line Items]
Long-Lived Assets	$ 1,163.3				$ 1,471.5				$ 1,163.3	$ 1,471.5
Total revenues	1,384.3	$ 1,263.1	$ 1,203.3	$ 1,140.4	1,128.8	$ 1,026.5	$ 1,045.0	$ 930.9	$ 4,991.1	$ 4,131.2	$ 3,551.1
Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									20.80%	16.40%
Soliris
Revenue from External Customer [Line Items]
Total revenues									$ 3,946.4	$ 3,563.0	3,144.1
Soliris \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									10.80%	13.30%
Ultomiris [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 338.9	$ 0.0	0.0
Strensiq
Revenue from External Customer [Line Items]
Total revenues									$ 592.5	$ 475.1	339.8
Strensiq \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									24.70%	39.80%
Kanuma
Revenue from External Customer [Line Items]
Total revenues									$ 112.2	$ 92.0	65.6
Kanuma \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									22.00%	40.20%
Product [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 4,990.0	$ 4,130.1	3,549.5
United States [Member]
Revenue from External Customer [Line Items]
Long-Lived Assets	272.8				468.3				272.8	468.3
United States [Member] \| Soliris
Revenue from External Customer [Line Items]
Total revenues									$ 2,014.0	$ 1,588.4	1,235.0
United States [Member] \| Soliris \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									26.80%	28.60%
United States [Member] \| Ultomiris [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 236.8	$ 0.0	0.0
United States [Member] \| Strensiq
Revenue from External Customer [Line Items]
Total revenues									$ 451.7	$ 374.3	280.1
United States [Member] \| Strensiq \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									20.70%	33.60%
United States [Member] \| Kanuma
Revenue from External Customer [Line Items]
Total revenues									$ 60.0	$ 51.3	42.4
United States [Member] \| Kanuma \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									17.00%	21.00%
Europe [Member]
Revenue from External Customer [Line Items]
Long-Lived Assets	889.6				1,001.1				$ 889.6	$ 1,001.1
Europe [Member] \| Soliris
Revenue from External Customer [Line Items]
Total revenues									$ 1,049.8	$ 1,036.7	985.2
Europe [Member] \| Soliris \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									1.30%	5.20%
Europe [Member] \| Ultomiris [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 52.2	$ 0.0	0.0
Europe [Member] \| Strensiq
Revenue from External Customer [Line Items]
Total revenues									$ 77.0	$ 61.7	35.6
Europe [Member] \| Strensiq \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									24.80%	73.30%
Europe [Member] \| Kanuma
Revenue from External Customer [Line Items]
Total revenues									$ 27.1	$ 21.6	14.6
Europe [Member] \| Kanuma \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									25.50%	47.90%
Asia Pacific [Member] \| Soliris
Revenue from External Customer [Line Items]
Total revenues									$ 423.5	$ 382.0	328.1
Asia Pacific [Member] \| Soliris \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									10.90%	16.40%
Asia Pacific [Member] \| Ultomiris [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 49.9	$ 0.0	0.0
Asia Pacific [Member] \| Strensiq
Revenue from External Customer [Line Items]
Total revenues									$ 50.4	$ 27.9	18.6
Asia Pacific [Member] \| Strensiq \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									80.60%	50.00%
Asia Pacific [Member] \| Kanuma
Revenue from External Customer [Line Items]
Total revenues									$ 4.6	$ 3.7	2.7
Asia Pacific [Member] \| Kanuma \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									24.30%	37.00%
Non-US, Excluding Europe And Asia Pacific [Member] \| Soliris
Revenue from External Customer [Line Items]
Total revenues									$ 459.1	$ 555.9	595.8
Non-US, Excluding Europe And Asia Pacific [Member] \| Soliris \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									(17.40%)	(6.70%)
Non-US, Excluding Europe And Asia Pacific [Member] \| Ultomiris [Member]
Revenue from External Customer [Line Items]
Total revenues									$ 0.0	$ 0.0	0.0
Non-US, Excluding Europe And Asia Pacific [Member] \| Strensiq
Revenue from External Customer [Line Items]
Total revenues									$ 13.4	11.2	5.5
Non-US, Excluding Europe And Asia Pacific [Member] \| Strensiq \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									19.60%
Non-US, Excluding Europe And Asia Pacific [Member] \| Kanuma
Revenue from External Customer [Line Items]
Total revenues									$ 20.5	15.4	$ 5.9
Non-US, Excluding Europe And Asia Pacific [Member] \| Kanuma \| Sales Revenue, Net [Member] \| Geographic Concentration Risk [Member]
Revenue from External Customer [Line Items]
Percentage change in product sales									33.10%
Other Country [Member]
Revenue from External Customer [Line Items]
Long-Lived Assets	$ 0.9				$ 2.1				$ 0.9	$ 2.1

Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Nov. 30, 2018	May 25, 2018
Quarterly Financial Information [Line Items]
Total revenues	$ 1,384.3	$ 1,263.1	$ 1,203.3	$ 1,140.4	$ 1,128.8	$ 1,026.5	$ 1,045.0	$ 930.9	$ 4,991.1	$ 4,131.2	$ 3,551.1
Cost of sales	114.3	95.2	99.2	85.8	96.8	90.6	95.3	91.6	394.5	374.3	454.2
Gross Profit	1,270.0	1,167.9	1,104.1	1,054.6	1,032.0	935.9	949.7	839.3
Total operating expenses	729.0	637.9	571.5	537.8	988.3	577.3	1,349.8	571.9	2,476.2	3,487.3	2,469.5
Operating income	541.0	530.0	532.6	516.8	43.7	358.6	(400.1)	267.4	2,120.4	269.6	627.4
Net income (loss)	$ 889.0	$ 467.6	$ 459.8	$ 587.9	$ (45.0)	$ 330.9	$ (457.4)	$ 249.1	$ 2,404.3	$ 77.6	$ 443.3
Earnings per common share
Basic (in dollars per share)	$ 4.02	$ 2.09	$ 2.05	$ 2.63	$ (0.20)	$ 1.48	$ (2.05)	$ 1.12	$ 10.77	$ 0.35	$ 1.98
Diluted (in dollars per share)	$ 4.00	$ 2.08	$ 2.04	$ 2.61	$ (0.20)	$ 1.47	$ (2.05)	$ 1.11	$ 10.70	$ 0.35	$ 1.97
Deferred tax benefit									$ 455.5	$ (32.9)	$ 45.9
Effective income tax rate reconciliation, Tax Cuts and Jobs Act of 2017, amount										(56.5)	$ 45.8
In Process Research and Development [Member]
Earnings per common share
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, Finite-Lived Intangibles													$ 803.7
Syntimmune, Inc [Member]
Earnings per common share
Asset Acquisition, Recognized Identifiable Assets Acquired And Liabilities Assumed, In-Process Research And Development					$ 379.3					$ 379.3		$ 375.2
Syntimmune, Inc [Member] \| In Process Research and Development [Member]
Earnings per common share
Asset Acquisition, Recognized Benefit From Previously Acquired Research And Development			$ 4.1
Intellectual Property Election [Member]
Earnings per common share
Deferred tax benefit, asset transfer	$ 382.2
Intellectual Property Election [Member] \| Wilson Therapeutics [Member]
Earnings per common share
Deferred tax benefit				$ 95.7					95.7
Valuation Allowance Release [Member]
Earnings per common share
Deferred tax benefit				$ 30.3					$ 30.3

Fair Value Measurement (Schedule Of Assets And Liabilites Measured At Fair Value) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives, Fair Value	$ 30.5	$ 60.9
Contingent consideration	192.4	183.2
Acquisition Related Contingent Consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	192.4
Cash Equivalents [Member] \| Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20.6	0.2
Cash Equivalents [Member] \| Corporate Bond Securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0.0	0.0
Cash Equivalents [Member] \| Corporate Bond Securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	20.6	0.2
Cash Equivalents [Member] \| Corporate Bond Securities [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0.0	0.0
Cash Equivalents [Member] \| Institutional Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	635.9	569.4
Cash Equivalents [Member] \| Institutional Money Market Funds [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0.0
Cash Equivalents [Member] \| Institutional Money Market Funds [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	635.9	569.4
Cash Equivalents [Member] \| Institutional Money Market Funds [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		0.0
Cash Equivalents [Member] \| Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	227.9	35.4
Cash Equivalents [Member] \| Commercial Paper [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0.0	0.0
Cash Equivalents [Member] \| Commercial Paper [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	227.9	35.4
Cash Equivalents [Member] \| Commercial Paper [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0.0	0.0
Cash Equivalents [Member] \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	19.2
Cash Equivalents [Member] \| Certificates of Deposit [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0
Cash Equivalents [Member] \| Certificates of Deposit [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	19.2
Cash Equivalents [Member] \| Certificates of Deposit [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0
Cash Equivalents [Member] \| Other Government Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	60.4	8.2
Cash Equivalents [Member] \| Other Government Obligations [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Cash Equivalents [Member] \| Other Government Obligations [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	60.4	8.2
Cash Equivalents [Member] \| Other Government Obligations [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Corporate Bond Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	3.7	122.6
Marketable Securities [Member] \| Corporate Bond Securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Corporate Bond Securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	3.7	122.6
Marketable Securities [Member] \| Corporate Bond Securities [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	19.0	16.7
Marketable Securities [Member] \| Commercial Paper [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Commercial Paper [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	19.0	16.7
Marketable Securities [Member] \| Commercial Paper [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Certificates of Deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	8.2	33.2
Marketable Securities [Member] \| Certificates of Deposit [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Certificates of Deposit [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	8.2	33.2
Marketable Securities [Member] \| Certificates of Deposit [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Mutual Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	23.1	16.5
Marketable Securities [Member] \| Mutual Funds [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	23.1	16.5
Marketable Securities [Member] \| Mutual Funds [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Mutual Funds [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Other Government Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	10.0	9.3
Marketable Securities [Member] \| Other Government Obligations [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Marketable Securities [Member] \| Other Government Obligations [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	10.0	9.3
Marketable Securities [Member] \| Other Government Obligations [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Other Assets [Member] \| Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	79.0	90.8
Other Assets [Member] \| Equity Securities [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	51.2	8.9
Other Assets [Member] \| Equity Securities [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	27.8	81.9
Other Assets [Member] \| Equity Securities [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	0.0	0.0
Other Non Current Assets \| Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	0.6	0.3
Other Non Current Assets \| Foreign Exchange Forward [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	0.0	0.0
Other Non Current Assets \| Foreign Exchange Forward [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	0.6	0.3
Other Non Current Assets \| Foreign Exchange Forward [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	0.0	0.0
Currentportionofcontingentconsideration [Member] \| Acquisition Related Contingent Consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration		97.6
Currentportionofcontingentconsideration [Member] \| Acquisition Related Contingent Consideration [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration		0.0
Currentportionofcontingentconsideration [Member] \| Acquisition Related Contingent Consideration [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration		0.0
Currentportionofcontingentconsideration [Member] \| Acquisition Related Contingent Consideration [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration		97.6
Other Current Liabilities [Member] \| Other Contingent Payments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	24.0
Other Current Liabilities [Member] \| Other Contingent Payments [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	0.0
Other Current Liabilities [Member] \| Other Contingent Payments [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	0.0
Other Current Liabilities [Member] \| Other Contingent Payments [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	24.0
Other Current Liabilities [Member] \| Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	26.6	18.8
Other Current Liabilities [Member] \| Foreign Exchange Forward [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	0.0	0.0
Other Current Liabilities [Member] \| Foreign Exchange Forward [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	26.6	18.8
Other Current Liabilities [Member] \| Foreign Exchange Forward [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	0.0	0.0
Other Current Liabilities [Member] \| Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	19.5	0.8
Other Current Liabilities [Member] \| Interest Rate Contract [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	0.0	0.0
Other Current Liabilities [Member] \| Interest Rate Contract [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	19.5	0.8
Other Current Liabilities [Member] \| Interest Rate Contract [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	0.0	0.0
Other Liabilities \| Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	41.9	17.3
Other Liabilities \| Interest Rate Contract [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	0.0	0.0
Other Liabilities \| Interest Rate Contract [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	41.9	17.3
Other Liabilities \| Interest Rate Contract [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value	0.0	0.0
Other Non Current Liabilities [Member] \| Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	1.1	3.1
Other Non Current Liabilities [Member] \| Foreign Exchange Forward [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	0.0	0.0
Other Non Current Liabilities [Member] \| Foreign Exchange Forward [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	1.1	3.1
Other Non Current Liabilities [Member] \| Foreign Exchange Forward [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, liability	0.0	0.0
Prepaid Expenses and Other Current Assets [Member] \| Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value		20.1
Prepaid Expenses and Other Current Assets [Member] \| Interest Rate Contract [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value		0.0
Prepaid Expenses and Other Current Assets [Member] \| Interest Rate Contract [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value		20.1
Prepaid Expenses and Other Current Assets [Member] \| Interest Rate Contract [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Rate Derivative Assets, at Fair Value		0.0
Prepaid Expenses and Other Current Assets [Member] \| Foreign Exchange Forward [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	29.9	40.5
Prepaid Expenses and Other Current Assets [Member] \| Foreign Exchange Forward [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	0.0	0.0
Prepaid Expenses and Other Current Assets [Member] \| Foreign Exchange Forward [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	29.9	40.5
Prepaid Expenses and Other Current Assets [Member] \| Foreign Exchange Forward [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign exchange forward contracts, asset	0.0	0.0
Contingent Consideration [Member] \| Acquisition Related Contingent Consideration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	192.4	183.2
Contingent Consideration [Member] \| Acquisition Related Contingent Consideration [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	0.0	0.0
Contingent Consideration [Member] \| Acquisition Related Contingent Consideration [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	0.0	0.0
Contingent Consideration [Member] \| Acquisition Related Contingent Consideration [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration	192.4	183.2
Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member] \| Other Non Current Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives, Fair Value		0.0
Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member] \| Other Non Current Assets \| Interest Rate Contract [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives, Fair Value	0.0
Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member] \| Prepaid Expenses and Other Current Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives, Fair Value		$ 20.1
Designated as Hedging Instrument [Member] \| Interest Rate Contract [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Interest Rate Contract [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Derivatives, Fair Value	$ 0.0