United Therapeutics (UTHR) 10-K26 Feb 202019 FY Annual reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2019	Feb. 19, 2020	Jun. 30, 2019
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	0-26301
Entity Registrant Name	United Therapeutics Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	52-1984749
Entity Address, Address Line One	1040 Spring Street
Entity Address, City or Town	Silver Spring
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20910
City Area Code	301
Local Phone Number	608-9292
Security 12b Title	Common Stock, par value $.01 per share
Trading Symbol	UTHR
Security Exchange Name	NASDAQ
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 Common Stock, Shares Outstanding		43,884,990
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001082554
Amendment Flag	false
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 2,976,670,801

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 738.4	$ 669.2
Marketable investments	747.5	746.7
Accounts receivable, no allowance for 2019 and 2018	151.4	175.7
Inventories, net	93.4	101
Other current assets	133.8	75.4
Total current assets	1,864.5	1,768
Marketable investments	767.5	442.6
Goodwill and other intangible assets, net	158.3	170.8
Property, plant and equipment, net	738.5	699.7
Deferred tax assets, net	230	95.7
Other non-current assets	154.6	224.2
Total assets	3,913.4	3,401
Current liabilities:
Accounts payable and accrued expenses	148.4	166.1
Line of credit (current)	250
Share tracking awards plan	25	72.2
Other current liabilities	39.6	38.3
Total current liabilities	463	276.6
Line of credit (non-current)	600	250
Other non-current liabilities	70	66.6
Total liabilities	1,133	593.2
Commitments and contingencies-Note 13
Temporary equity		19.2
Stockholders' equity:
Common stock, par value $.01, 245,000,000 shares authorized, 70,503,775 and 70,207,581 shares issued, and 43,884,559 and 43,588,365 shares outstanding at December 31, 2019 and 2018, respectively	0.7	0.7
Additional paid-in capital	2,047.9	1,940.2
Accumulated other comprehensive loss	(14.2)	(7.9)
Treasury stock, 26,619,216 shares at December 31, 2019 and 2018	(2,579.2)	(2,579.2)
Retained earnings	3,325.2	3,434.8
Total stockholders' equity	2,780.4	2,788.6
Total liabilities and stockholders' equity	3,913.4	3,401
Preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued
Series A junior participating preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accounts receivable, allowance (in dollars)	$ 0	$ 0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	245,000,000	245,000,000
Common stock, shares issued	70,503,775	70,207,581
Common stock, shares outstanding	43,884,559	43,588,365
Treasury stock, shares	26,619,216	26,619,216
Preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Series A junior participating preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Total revenues	$ 1,448.8	$ 1,627.8	$ 1,725.3
Operating expenses:
Cost of product sales	117.6	198.7	105.7
Research and development	1,182.6	357.9	264.6
Selling, general and administrative	336.2	265.8	330.1
Settlement of loss contingency			210
Total operating expenses	1,636.4	822.4	910.4
Operating (loss) income	(187.6)	805.4	814.9
Interest income	44.2	28.6	10.9
Interest expense	(44.2)	(13.9)	(9)
Other income (expense), net	22.6	(7.7)	2.3
Impairments of investments in privately-held companies		(53.5)	(49.6)
Total other income (expense), net	22.6	(46.5)	(45.4)
(Loss) income before income taxes	(165)	758.9	769.5
Income tax benefit (expense)	60.5	(169.7)	(351.6)
Net (loss) income	$ (104.5)	$ 589.2	$ 417.9
Net (loss) income per common share:
Basic (in dollars per share)	$ (2.39)	$ 13.54	$ 9.50
Diluted (in dollars per share)	$ (2.39)	$ 13.39	$ 9.31
Weighted average number of common shares outstanding:
Basic (in shares)	43.8	43.5	44
Diluted (in shares)	43.8	44	44.9
Net product sales
Revenues:
Total revenues	$ 1,448.8	$ 1,627.8	$ 1,725.3

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Comprehensive income:
Net (loss) income	$ (104.5)	$ 589.2	$ 417.9
Other comprehensive (loss) income:
Foreign currency translation gains			0.2
Defined benefit pension plan:
Actuarial (loss) gain arising during period, net of tax	(10.6)	10.7	(1.7)
Amortization of actuarial gain and prior service cost included in net periodic pension cost and settlement, net of tax	(1.7)	1.4	0.6
Total defined benefit pension plan, net of tax	(12.3)	12.1	(1.1)
Unrealized gain (loss) on available-for-sale securities, net of tax	6	(0.4)	(1.9)
Other comprehensive (loss) income, net of tax	(6.3)	11.7	(2.8)
Comprehensive (loss) income	$ (110.8)	$ 600.9	$ 415.1

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Treasury Stock	Retained Earnings	Total
Balance at Dec. 31, 2016	$ 0.7	$ 1,813.5	$ (16.8)	$ (2,379.6)	$ 2,433.5	$ 1,851.3
Balance (in shares) at Dec. 31, 2016	69.3
Increase (Decrease) in Stockholders' Equity
Net (loss) income					417.9	417.9
Foreign currency translation adjustments			0.2			0.2
Unrealized gain (loss) on available-for-sale securities			(1.9)			(1.9)
Defined benefit pension plan			(1.1)			(1.1)
Shares issued under employee stock purchase plan		4.1				4.1
Shares issued under employee stock purchase plan (in shares)	0.1
Shares issued upon expiration of warrants		(53.2)		53.2
Repurchase of shares		2.8		(252.8)		(250)
Exercise of stock options		39.9				39.9
Exercise of stock options (in shares)	0.5
Share-based compensation		46.4				46.4
Cumulative effect of accounting change		0.7			(5.8)	(5.1)
Consolidation of variable interest entity		0.1				0.1
Balance at Dec. 31, 2017	$ 0.7	1,854.3	(19.6)	(2,579.2)	2,845.6	2,101.8
Balance (in shares) at Dec. 31, 2017	69.9
Increase (Decrease) in Stockholders' Equity
Net (loss) income					589.2	589.2
Unrealized gain (loss) on available-for-sale securities			(0.4)			(0.4)
Defined benefit pension plan			12.1			12.1
Shares issued under employee stock purchase plan		3.9				3.9
Restricted stock units withheld for taxes		(0.1)				(0.1)
Exercise of stock options		15.6				15.6
Exercise of stock options (in shares)	0.3
Share-based compensation		66.5				66.5
Balance at Dec. 31, 2018	$ 0.7	1,940.2	(7.9)	(2,579.2)	3,434.8	2,788.6
Balance (in shares) at Dec. 31, 2018	70.2
Increase (Decrease) in Stockholders' Equity
Net (loss) income					(104.5)	(104.5)
Unrealized gain (loss) on available-for-sale securities			6			6
Defined benefit pension plan			(12.3)			(12.3)
Shares issued under employee stock purchase plan		4.1				4.1
Common stock issued upon RSUs vesting (in shares)	0.1
Restricted stock units withheld for taxes		(2.1)				(2.1)
Exercise of stock options		9.9				9.9
Exercise of stock options (in shares)	0.2
Share-based compensation		85.1				85.1
Cumulative effect of accounting change					(5.1)	(5.1)
Reclassification from temporary equity to permanent equity		10.8				10.8
Deconsolidation of variable interest entity		(0.1)				(0.1)
Balance at Dec. 31, 2019	$ 0.7	$ 2,047.9	$ (14.2)	$ (2,579.2)	$ 3,325.2	$ 2,780.4
Balance (in shares) at Dec. 31, 2019	70.5

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Common stock subject to repurchase		$ 10.8
Temporary equity common stock subject to repurchase
Common stock subject to repurchase			$ 10.8
Common stock issued (in shares)	200,000
Common stock issued split (in shares)	400,000
Repurchase price (in dollars per share)	$ 27.21

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net (loss) income	$ (104.5)	$ 589.2	$ 417.9
Adjustments to reconcile net (loss) income to net cash (used in)/provided by operating activities:
Depreciation and amortization	45.9	35.9	31
Share-based compensation expense (benefit)	45.4	(26.4)	73.5
Impairments of investments in privately-held companies		53.5	49.6
Asset impairment charges	17.2
Other	(29.7)	1.8	(19.4)
Changes in operating assets and liabilities:
Accounts receivable	24.4	121.4	(82.7)
Inventories	12.9	9.3	(0.5)
Accounts payable and accrued expenses	(16.3)	(11)	66.2
Other assets and liabilities	(201.9)	4.7	(61.4)
Net cash (used in) provided by operating activities	(206.6)	778.4	474.2
Cash flows from investing activities:
Purchases of property, plant and equipment	(83.7)	(184.4)	(86.3)
Proceeds from sale of property, plant and equipment			8.3
Deposits		(46)
Purchases of held-to-maturity and other investments		(99.3)	(51.8)
Sales/maturities of held-to-maturity investments	39.7	88.6	52.9
Purchases of available-for-sale investments	(1,271.5)	(762.7)	(718.4)
Sales/maturities of available-for-sale investments	980.1	312.3	20
Sales of investments in equity securities	20.5
Purchases of investments in privately-held companies	(8)	(5)	(60.4)
Decrease in cash due to deconsolidation of variable interest entity	(12.5)
Consolidation of variable interest entity			0.1
Acquisition, net of cash acquired		(124.1)
Net cash used in investing activities	(335.4)	(820.6)	(835.6)
Cash flows from financing activities:
Proceeds from line of credit	800	250	250
Repayment of line of credit	(200)	(250)
Payments of debt issuance costs	(0.7)	(13.2)	(0.7)
Payments to repurchase common stock			(250)
Proceeds from the exercise of stock options	9.9	15.6	39.9
Proceeds from the issuance of stock under employee stock purchase plan	4.1	3.9	4.1
Restricted stock units withheld for taxes	(2.1)
Net cash provided by financing activities	611.2	6.3	43.3
Effect of exchange rate changes on cash and cash equivalents			0.2
Net increase (decrease) in cash and cash equivalents	69.2	(35.9)	(317.9)
Cash and cash equivalents, beginning of year	669.2	705.1	1,023
Cash and cash equivalents, end of year	738.4	669.2	705.1
Supplemental cash flow information:
Cash paid for interest	41	9.4	7.5
Cash paid for income taxes	120.2	102.7	346.9
Cash paid for settlement of loss contingency			210
Non-cash investing and financing activities:
Non-cash additions to property, plant and equipment	$ 54.5	$ 11.5	$ 11.5

Organization and Business Descr

Organization and Business Description	12 Months Ended
Organization and Business Description	Dec. 31, 2019
Organization and Business Description
Organization and Business Description	1. Organization and Business Description United Therapeutics Corporation is a biotechnology company focused on the development and commercialization of innovative products to address the unmet medical needs of patients with chronic and life-threatening conditions. We have approval from the U.S. Food and Drug Administration (FDA) to market the following therapies: Remodulin ® ® ® ® ® As used in these notes to our consolidated financial statements, unless the context otherwise requires, the terms “we”, “us”, “our”, and similar terms refer to United Therapeutics Corporation and its consolidated subsidiaries.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2019
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements of United Therapeutics Corporation and its consolidated subsidiaries have been prepared in accordance with accounting principles generally accepted in the United States (GAAP). All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of our consolidated financial statements in accordance with GAAP requires our management to make estimates and assumptions that affect reported amounts of assets and liabilities at the date of our consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. We base our estimates on assumptions regarding historical experience, currently available information and anticipated developments that we believe are reasonable and appropriate. However, because the use of estimates involves an inherent degree of uncertainty, actual results could differ from those estimates. Estimates are used for, but not limited to, revenue recognition, share-based compensation, determining the fair value of assets acquired and liabilities assumed in business combinations, marketable investments, fair value measurements (including those related to contingent consideration), inventory reserves, investments in privately-held companies, income taxes, goodwill and other intangible assets, and obligations related to our Supplemental Executive Retirement Plan. Fair Value Measurements Fair value is a market-based measurement, not an entity-specific measurement. The objective of a fair value measurement is to estimate the price to sell an asset or transfer a liability in an orderly transaction between market participants at the measurement date under current market conditions. Such transactions to sell an asset or transfer a liability are assumed to occur in the principal market for that asset or liability, or in the absence of the principal market, the most advantageous market for the asset or liability. 2. Summary of Significant Accounting Policies (Continued) Assets and liabilities subject to fair value measurement disclosures are required to be classified according to a three-level fair value hierarchy with respect to the inputs (or assumptions) used to determine fair value. The level in which an asset or liability is disclosed within the fair value hierarchy is based on the lowest level input that is significant to the related fair value measurement in its entirety. The guidance under the fair value measurement framework applies to other existing accounting guidance in the Financial Accounting Standards Board (FASB) codification that requires or permits fair value measurements. Refer to related disclosures in Note 5— Fair Value Measurements. Cash Equivalents Cash equivalents consist of highly liquid investments with maturities of three months or less from the date of acquisition. Marketable Investments Our marketable investments are primarily debt securities that we classify as available-for-sale. If we have both the positive intent and the ability to hold the securities until maturity, the securities are classified as held-to-maturity. We determine the appropriate classification of the securities at the time they are acquired and evaluate the appropriateness of such classifications at each balance sheet date. Available-for-sale debt securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive (loss) income in stockholders’ equity, until realized. Held-to-maturity debt securities are recorded at amortized cost, adjusted for the amortization of discounts or premiums. Related discounts and premiums are amortized over the term of these securities as an adjustment to the yield using the effective interest method. Marketable investments are classified as either current or non-current assets on our consolidated balance sheets based on their contractual maturity dates. We monitor our investment portfolio for impairment quarterly or more frequently if circumstances warrant. In the event that the carrying value of a debt security exceeds its fair value and the decline in value is determined to be other-than-temporary, we record an impairment charge within earnings attributable to the estimated credit loss. In determining whether a decline in the value of an investment is other-than-temporary, we evaluate currently available factors that may include, among others: (1) general market conditions; (2) the duration and extent to which fair value has been less than the carrying value; (3) the investment issuer’s financial condition and business outlook; and (4) our assessment as to whether it is more likely than not that we will be required to sell a security prior to recovery of its amortized cost basis. Inventories Inventories are stated at the lower of cost (first-in, first-out method) or net realizable value and consist of the following, net of reserves (in millions): As of December 31, 2019 2018 Raw materials $ 21.1 $ 24.3 Work-in-progress 29.1 28.0 Finished goods 43.2 48.7 Total inventories $ 93.4 $ 101.0 2. Summary of Significant Accounting Policies (Continued) Goodwill and Other Intangible Assets The carrying amount of goodwill is not amortized but is subject to annual impairment testing. We conduct our impairment testing of goodwill annually during the fourth quarter, or more frequently if impairment indicators exist. Initially, we evaluate various pertinent qualitative factors to assess whether it is more likely than not that the fair value of a reporting unit to which goodwill has been assigned is less than its carrying value. Such qualitative factors can include, among others: (1) industry and market conditions; (2) present and anticipated sales and cost factors; and (3) overall financial performance. If we conclude based on our qualitative assessment that it is more likely than not that the fair value of a reporting unit is less than its carrying value, we then measure the fair value of the reporting unit and compare its fair value to its carrying value (Step 1 of the goodwill impairment test). If the carrying amount of the reporting unit exceeds its fair value, then the amount of an impairment loss, if any, is measured as the excess of the recorded amount of goodwill over its implied fair value (Step 2 of the goodwill impairment test). We used a qualitative assessment for our goodwill impairment testing for 2019 and 2018. During the year ended December 31, 2019, we wrote off $3.5 million of goodwill related to the deconsolidation of a variable interest entity, as discussed below. There were no impairment losses related to goodwill during the year ended December 31, 2018. Indefinite-lived intangible assets are not amortized but are evaluated annually or more frequently for impairment if impairment indicators exist. Our indefinite-lived intangible assets include purchased in-process research and development (IPR&D) assets, which were measured at their estimated fair values as of their acquisition dates. We used a qualitative assessment for our indefinite-lived intangible asset impairment testing. During the year ended December 31, 2019, we recognized an impairment charge of $8.8 million related to an IPR&D asset associated with our terminated license agreement with the variable interest entity, as discussed below. There were no impairment losses related to indefinite-lived intangible assets during the year ended December 31, 2018. Intangible assets subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an intangible asset may not be recoverable. Impairment losses are measured and recognized to the extent the carrying value of such assets exceeds their fair value. We recorded no impairment losses during the years ended December 31, 2019 and 2018 related to intangible assets subject to amortization. Goodwill and other intangible assets comprise the following (in millions): As of December 31, 2019 As of December 31, 2018 Accumulated Accumulated Gross Amortization Net Gross Amortization Net Goodwill $ 28.0 $ — $ 28.0 $ 31.5 $ — $ 31.5 Other intangible assets: Technology, patents and trade names 6.7 (5.3) 1.4 6.7 (5.1) 1.6 In-process research and development (1) 128.9 — 128.9 137.7 — 137.7 Total $ 163.6 $ (5.3) $ 158.3 $ 175.9 $ (5.1) $ 170.8 (1) In 2018, we determined the fair value of an IPR&D asset resulting from our acquisition of SteadyMed Ltd. using the multi-period earnings method under the income approach. This method reflects the present value of the projected cash flows that are expected to be generated by the IPR&D, less charges representing the required return on other assets to sustain those cash flows. 2. Summary of Significant Accounting Policies (Continued) In June 2019, we elected to terminate our license agreement with the variable interest entity (VIE) discussed under Note 4— Investments—Deconsolidation of a Variable Interest Entity Related amortization expense for the years ended December 31, 2019, 2018 and 2017, was $0.2 million, $0.1 million and $0.5 million, respectively. As of December 31, 2019, aggregate amortization expense related to definite intangible assets each succeeding Property, Plant and Equipment Property, plant and equipment is recorded at cost and depreciated over its estimated useful life using the straight-line method. The estimated useful lives of property, plant and equipment by major category are as follows: Land improvements 15 Years Buildings 25-39 Years Building improvements 10-39 Years Furniture, equipment and vehicles 3-25 Years Leasehold improvements Remaining lease term, or the estimated useful life of the improvement, whichever is shorter Property, plant and equipment consists of the following (in millions): As of December 31, 2019 2018 Land and land improvements $ 74.4 $ 69.0 Buildings, building improvements and leasehold improvements 573.3 533.3 Buildings under construction 42.0 126.5 Furniture, equipment and vehicles 318.2 205.5 1,007.9 934.3 Less—accumulated depreciation (269.4) (234.6) Property, plant and equipment, net $ 738.5 $ 699.7 Depreciation expense for the years ended December 31, 2019, 2018 and 2017, was $45.7 million, $35.8 million and $30.5 million, respectively. In connection with the completion of construction in the third quarter of 2019 of a building we own, we leased part of the space in the building to another entity as part of a broader collaboration. In 2019, we reclassified $23.7 million of property, plant and equipment, net to other non-current assets on our consolidated balance sheets. For more information, refer to Note 3— Recently Issued Accounting Standards—Accounting Standards Adopted. 2. Summary of Significant Accounting Policies (Continued) Buildings under construction consists of direct costs related to our construction projects. Investments in Privately-Held Companies We measure our non-controlling equity investments in privately-held companies using the measurement alternative because the fair values of these investments are not readily determinable. Under this alternative, the investments are measured at cost, less any impairment, adjusted for any observable price changes. We monitor these investments individually for any observable price changes or impairment indicators. We adjust the measurement of these investments for observable price changes in orderly transactions for the identical or a similar investment of the same issuer. We consider relevant transactions, including any potential funding opportunities, which occur on or before the balance sheet date in evaluating whether any observable price changes have occurred. When a relevant transaction is identified, a careful review of the attendant rights and obligations is necessary to evaluate whether such transaction is deemed to be a similar or identical investment. We include our investments in privately-held companies within other non-current assets on our consolidated balance sheets. These investments are subject to a periodic impairment review and if impaired, the investment is measured and recorded at fair value in accordance with ASC 820, Fair Value Measurements Treasury Stock Repurchased treasury stock is recorded at cost, including commissions and fees. The cost of treasury shares sold or reissued is determined using the first-in, first-out method. Related gains and losses on sales of treasury stock are recognized as adjustments to stockholders’ equity. Revenue Recognition On January 1, 2018, we adopted Topic 606 using the modified retrospective approach applied to those contracts in effect as of January 1, 2018. Under this transition method, results for reporting periods beginning after January 1, 2018 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported in accordance with our historical accounting under Topic 605, Revenue Recognition To determine revenue recognition for contractual arrangements that we determine are within the scope of Topic 606, we perform the following five steps: (1) identify each contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to our performance obligations in the contract; and (5) recognize revenue when (or as) we satisfy the relevant performance obligation. We only apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. 2. Summary of Significant Accounting Policies (Continued) We generate revenues from the sale of our five commercially approved products: Remodulin, Tyvaso, Orenitram, Unituxin and Adcirca. We recognize revenue when we transfer control of our products to our distributors, as our contracts have a single performance obligation (delivery of our product). Except for Adcirca sales, the performance obligation is generally satisfied when our products are delivered to the distributor’s designated location. We recognize revenue from Adcirca sales upon shipment from an Eli Lilly and Company (Lilly) distribution center. Future revenue from delivery of our products will be based on purchase orders provided to us by our distributors. We are not required to disclose the value of unsatisfied performance obligations as our contracts have a non-cancelable duration of one year or less. See Note 14— Segment Information Gross-to-Net Deductions As is customary in the pharmaceutical industry, our product sales are recorded net of various forms of gross-to-net deductions. These deductions vary the consideration to which we are entitled in exchange for the sale of our products to our distributors, and include reserves for: (1) rebates and chargebacks; (2) prompt payment discounts; (3) allowance for sales returns; and (4) distributor fees and other allowances. We estimate these reserves in the same period that we recognize revenue for product sales to distributors. The net product sales amount recognized represents the amount we believe will not be subject to a significant future reversal of revenue. Estimating gross-to-net deductions involves the use of significant assumptions and judgments, as well as information obtained from external sources. For our rebate and chargeback liabilities, in particular, the time lag experienced in the payment of the rebate or chargeback may result in revisions of these accruals in future periods. However, based on our significant history and experience estimating these accruals and our development of these accruals based on the expected value method, we do not believe there will be significant changes to our estimates recorded during the period of sale. We recognized an aggregate $2.3 million decrease in our net product sales for the year ended December 31, 2019 and an aggregate $8.8 million increase in our net product sales for the year ended December 31, 2018, related to revenue recognized from product sales in prior periods. In 2018 we recorded a change in estimate that resulted in the reversal of an estimated liability for Medicaid rebates of $13.6 million, which had initially been recorded in 2017. Additional adjustments to accruals for prior periods primarily related to our participation in state Medicaid programs and contracts with commercial payers. 2. Summary of Significant Accounting Policies (Continued) Rebates and chargebacks. Prompt payment discounts. Product returns. For Unituxin, we ship product with expiration dates that are generally 9 to 14 months after the initial sale. However, our historical returns have not been material and, therefore, we do not record a returns allowance for Unituxin. For sales of our other commercial products, we do not offer our customers a general right of return. 2. Summary of Significant Accounting Policies (Continued) Distributor fees and other allowances. Trade Receivables We invoice and receive payment from our customers after we recognize revenue, resulting in receivables from our customers that are presented as accounts receivable on our consolidated balance sheets. Accounts receivable consist of short-term amounts due from our distributors (generally 30 to 90 days) and are stated at the amount we expect to collect. We establish an allowance for doubtful accounts, if deemed necessary, based on our assessment of the collectability of specific distributor accounts. We did not recognize any impairment losses for accounts receivable for each of the years ended December 31, 2019 and 2018. Changes in accounts receivable are primarily due to the timing and magnitude of orders of our products, the timing of when control of our products is transferred to our distributors and the timing of cash collections. Adcirca Adcirca is manufactured for us by Lilly and distributed through its pharmaceutical wholesaler network on our behalf. Specifically, Lilly handles all of the administrative functions associated with the sale of Adcirca on our behalf, including the receipt and processing of customer purchase orders, shipment to customers, and invoicing and collection of customer payments. We recognize sales of Adcirca on a gross basis (net of reserves for gross-to-net deductions) based on our determination that we are acting as a principal due to our control of the product prior to its transfer to our customers. Our control is evidenced by our substantive ownership of product inventory, the fact that we bear all inventory risks, our primary responsibility for the acceptability of the product to our customers, and our ability to influence net product sales through our contracting decisions with commercial payers and participation in governmental-funded programs. Research and Development Research and development costs are expensed as incurred except for refundable payments made in advance of services to be provided to us. Related expenses consist of internal labor and overhead, costs to acquire pharmaceutical products and product rights for development, materials used in clinical trials and amounts paid to third parties for services and materials related to drug development and clinical trials. As part of our business strategy, we may in-license the rights to develop and commercialize product candidates. For each in-license transaction, we evaluate whether we have acquired processes or activities along with inputs that would be sufficient to constitute a “business” as defined under GAAP. As defined under GAAP, a “business” consists of inputs and processes applied to those inputs that have the ability to create outputs. Although businesses usually have outputs, outputs are not required for an integrated set of activities to qualify as a business. When we determine that we have not acquired sufficient processes or activities to constitute a business, any up-front payments, as well as pre-commercial milestone payments, are immediately expensed as acquired IPR&D in the period in which they are incurred. Milestone payments made to third parties subsequent to regulatory approval are capitalized as intangible assets and amortized over the estimated remaining useful life of the related product. 2. Summary of Significant Accounting Policies (Continued) We recognize the following costs, among others, as research and development expense in the period related costs are incurred: ● costs associated with in-house or contracted manufacturing activities prior to receiving FDA approval for such facilities, or for major unproven changes to our manufacturing processes; ● costs incurred in-licensing the rights to technologies in the research and development stage that have no alternative future use; and ● up-front payments made in connection with arrangements to obtain license and distribution rights to pharmaceutical product candidates prior to regulatory approval, absent any alternative future use. Share-Based Compensation Generally, the fair value of a stock option grant is measured on its grant date and related compensation expense is recognized ratably over the requisite service period. We issue new shares of our common stock upon the exercise of stock options. Additionally, certain executives have stock options with performance conditions that have vesting rights tied to achievement of specific targeted criteria. Share-based compensation expense for all awards is recorded ratably over their vesting period, depending on the specific terms of the award and achievement of the specified performance conditions. Refer to Note 9— Share-Based Compensation We measure the fair value of restricted stock units using the stock price on the date of grant and related compensation expense is recognized ratably over the vesting period. Each restricted stock unit entitles the holder to receive one share of our common stock upon vesting. We issue new shares of our common stock upon the vesting of restricted stock units. Awards under our share tracking awards plans require cash settlement upon exercise and are classified as a liability. Accordingly, the fair value of related cash-settled awards is re-measured at each reporting date until awards are exercised or are otherwise no longer outstanding. Related changes in the fair value of outstanding cash-settled awards at each financial reporting date are recognized as adjustments to share-based compensation expense. We measure the fair value of stock to be purchased through our employee stock purchase plan at the beginning of an offering period, or grant date, and recognize related compensation expense ratably over the requisite service period (the offering period). We issue new shares of our common stock upon the end of each offering period, or exercise date. Income Taxes We account for income taxes in accordance with the asset and liability method. Under this method, we determine deferred tax assets and liabilities based on the difference between the financial statement carrying amounts and the tax bases of assets and liabilities, using enacted tax rates in effect for years in which the temporary differences are expected to reverse. We apply a valuation allowance against any net deferred tax asset if, based on the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. 2. Summary of Significant Accounting Policies (Continued) We recognize the benefit of an uncertain tax position that has been taken or that we expect to take on income tax returns only if such tax position is more likely than not to be sustained. We recognize the benefit in an amount equal to the largest amount that we determine has a greater than 50 percent likelihood of being realized upon settlement. The ultimate resolution of uncertain tax positions could result in amounts different from those recognized in our consolidated financial statements. Earnings per Share Basic (loss) earnings per share is computed by dividing net (loss) income by the weighted average number of shares of common stock outstanding during the period. Diluted (loss) earnings per common share is computed by dividing net (loss) income by the weighted average number of shares of common stock outstanding during the period, plus the potential dilutive effect of other securities if such securities were converted or exercised. During periods in which we incur net losses, both basic and diluted loss per share are calculated by dividing the net loss by the weighted average shares outstanding. Potentially dilutive securities are excluded from the calculation because their effect would be anti-dilutive. Concentration of Credit Risk Financial instruments that are exposed to credit risk consist of cash, money market funds, certificates of deposit, marketable debt securities, and trade receivables. We maintain our cash and money market funds with financial institutions that are federally insured. While balances deposited in these institutions often exceed Federal Deposit Insurance Corporation limits, we have not experienced any losses on related accounts to date. Furthermore, we limit our risk exposure by maintaining funds in financial institutions that we believe are creditworthy and financially sound. Our investments in marketable debt securities have been issued by corporate entities and government-sponsored enterprises with high credit ratings. We mitigate investment risks by investing in highly-rated securities with relatively short maturities that we believe do not subject us to undue investment or credit risk. In addition, our investment policy does not provide for investments in complex or structured financial instruments. At any given time, our trade receivables are concentrated among a small number of principal customers. If any of these financial institutions, issuers or customers fail to perform their obligations under the terms of these financial instruments, our maximum exposure to potential losses would be equal to amounts reported on our consolidated balance sheets.

Recently Issued Accounting Stan

Recently Issued Accounting Standards	12 Months Ended
Recently Issued Accounting Standards	Dec. 31, 2019
Recently Issued Accounting Standards
Recently Issued Accounting Standards	3. Recently Issued Accounting Standards Accounting Standards Adopted In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-02, Leases Leases (Topic 842)—Targeted Improvements Upon adoption of this standard, we recognized a right-of-use asset of $8.2 million, and a corresponding lease liability of the same amount, related to our operating leases as of January 1, 2019. In addition, we recognized a cumulative-effect adjustment for the de-recognition of our build-to-suit leases as these leases no longer qualify for build-to-suit accounting and have instead been recognized as operating leases under ASC 842. The adjustment resulted in a decrease to retained earnings of $5.1 million, which is net of a tax benefit. At adoption, our weighted average remaining lease term was 3.0 years and our weighted-average discount rate was 4.9%. Supplemental balance sheet information related to operating leases was as follows (in millions): Financial Statement Line Item on our December 31, January 1, Operating Leases Consolidated Balance Sheets 2019 2019 Right-of-use assets Other non-current assets $ 4.8 $ 8.2 Current lease liabilities Other current liabilities $ 1.8 $ 4.1 Non-current lease liabilities Other non-current liabilities 3.0 4.1 Total operating lease liabilities $ 4.8 $ 8.2 In connection with completion of construction in the third quarter of 2019 of a building we own, we leased part of the space in the building to another entity as part of a broader collaboration. The lease is accounted for as a sales-type lease. In 2019, we reclassified $23.7 million of property, plant and equipment, net to other non-current assets on our consolidated balance sheets. Our activities under the broader collaboration were immaterial for the year ended December 31, 2019. 3. Recently Issued Accounting Standards (Continued) In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, to eliminate or modify certain disclosure rules that are redundant, outdated, or duplicative of U.S. GAAP or other regulatory requirements. Among other changes, the amendments eliminated the annual requirement to disclose the high and low trading prices of our common stock. In addition, the amendments expanded the disclosure requirements related to the analysis of shareholders’ equity for interim financial statements. An analysis of the changes in each caption of shareholders’ equity presented in the balance sheet must be provided in a note or separate statement, and we provided this disclosure in a separate statement (Consolidated Statements of Stockholders’ Equity) beginning in the first quarter of 2019. In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) Revenue Recognition (Topic 605) Summary of Significant Accounting Policies Revenue Recognition Accounting Standards Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments 3. Recently Issued Accounting Standards (Continued) In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes ,

Investments

Investments	12 Months Ended
Investments	Dec. 31, 2019
Investments
Investments	4. Investments Marketable Investments Available-for-Sale Debt Securities Available-for-sale debt securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive loss in stockholders’ equity, until realized. Available-for-sale debt securities consisted of the following (in millions): Gross Gross Amortized Unrealized Unrealized Fair As of December 31, 2019 Cost Gains Losses Value U.S. government and agency securities $ 1,225.2 $ 2.9 $ (0.2) $ 1,227.9 Corporate debt securities 222.4 1.7 — 224.1 Total $ 1,447.6 $ 4.6 $ (0.2) $ 1,452.0 Reported under the following captions on our consolidated balance sheets: Current marketable investments 684.5 Non-current marketable investments 767.5 Total $ 1,452.0 Gross Gross Amortized Unrealized Unrealized Fair As of December 31, 2018 Cost Gains Losses Value U.S. government and agency securities $ 1,077.4 $ 0.7 $ (3.9) $ 1,074.2 Corporate debt securities 72.3 — (0.3) 72.0 Total $ 1,149.7 $ 0.7 $ (4.2) $ 1,146.2 Reported under the following captions on our consolidated balance sheets: Current marketable investments 705.8 Non-current marketable investments 440.4 Total $ 1,146.2 The following table summarizes the contractual maturities of available-for-sale marketable investments (in millions): As of December 31, 2019 Amortized Fair Cost Value Due within one year $ 683.3 $ 684.5 Due in one to three years 764.3 767.5 Total $ 1,447.6 $ 1,452.0 4. Investments (Continued) Held-to-Maturity Investments Our current and long-term marketable investments included zero and $39.6 million of investments classified as held-to-maturity as of December 31, 2019 and 2018, respectively. Marketable investments classified as held-to-maturity were comprised of government-sponsored enterprises and corporate notes and bonds. We did not intend to sell these securities, nor was it more likely than not that we would be required to sell them prior to the recovery of their amortized cost basis. Furthermore, we did not believe that these securities exposed us to undue market risk or counterparty credit risk. As such, we did not consider these securities to be other than temporarily impaired. Investments in Equity Securities with Readily Determinable Fair Values We held investments in equity securities with readily determinable fair values of $63.0 million and $3.5 million as of December 31, 2019 and December 31, 2018, respectively, which are included in current marketable investments on our consolidated balance sheets. In 2019, two of the privately-held companies in which we had invested, completed their initial public offerings and their common stock began trading on the Nasdaq Stock Market. As a result, the equity securities we own in these companies are now recorded at fair value rather than reflected as investments in privately-held companies. Changes in the fair value of publicly traded equity securities are recorded on our consolidated statements of operations within other income (expense), net. Refer to Note 5-Fair Value Measurements. Investments in Privately-Held Companies As of December 31, 2019, we maintained non-controlling equity investments in privately-held companies of $86.0 million in the aggregate. Adjustments to the carrying values of these securities were not material for the years ended December 31, 2019 and 2018. We made payments of $8.0 million and $5.0 million for investments in privately-held companies during the years ended December 31, 2019 and 2018, respectively. During the years ended December 31, 2019, 2018 and 2017, we recorded zero, $53.5 million and $49.6 million , respectively, of impairment charges related to our investments in privately-held companies. Consolidation of a Variable Interest Entity In August 2019, we entered into an operating agreement and trust agreement related to the expected contribution of an asset to a newly created trust of which we are the beneficiary. The trust was created for legal and administrative purposes and is not expected to make future purchases. As the operator of the asset, we are required to incur all future expenses related to the operation and maintenance of the asset. Accordingly, the trust is deemed a VIE because it relies on our capital to sustain future operating expenses. We are deemed the primary beneficiary of the VIE because we are the sole provider of financial support and can unilaterally remove the trustee without cause. Accordingly, we consolidate the VIE’s balance sheet and results of operations. As of December 31, 2019, our consolidated balance sheets included a $57.6 million asset due to the consolidation of this VIE included within property, plant and equipment, net. During the fourth quarter of 2019, the asset in the trust was reclassified from other non-current assets to property, plant and equipment, net on our consolidated balance sheets upon being placed into service. Upon consolidating the VIE, which was not deemed a business as defined in ASC 805, Business Combinations 4. Investments (Continued) Deconsolidation of a Variable Interest Entity In April 2017, we made a $7.5 million minority equity investment in a privately-held company. In addition to our investment, we entered into an exclusive license, development and commercialization agreement (the License Agreement) with this company. The License Agreement entitled us to control rights sufficient to require us to regard the company as a VIE and to consolidate the company’s balance sheet and results of operations as the primary beneficiary of this company. In June 2019, we elected to terminate the License Agreement. The termination of the License Agreement caused us to impair an associated IPR&D asset during the second quarter of 2019 and recognize an impairment charge of $8.8 million, which is included within research and development expense on our consolidated statements of operations. Upon effectiveness of the termination of the License Agreement in the third quarter of 2019, we no longer have the power to direct the entity’s activities. Consequently, we deconsolidated the entity in the third quarter of 2019. Our deconsolidation of the entity’s balance sheet, which included $3.5 million of goodwill and $8.4 million of temporary equity, resulted in a net deconsolidation loss of $2.0 million. We have no further obligations to fund the entity, and our maximum exposure to loss is equal to the carrying value of our retained interest. We now account for our equity investment in this privately-held company using the equity method of accounting because we have the ability to exercise significant influence over the operating and financial policies of the entity, but we no longer have a controlling financial interest.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
Fair Value Measurements	Dec. 31, 2019
Fair Value Measurements
Fair Value Measurements	5. Fair Value Measurements Assets and liabilities subject to fair value measurements are required to be disclosed within a fair value hierarchy. The fair value hierarchy ranks the quality and reliability of inputs used to determine fair value. Accordingly, assets and liabilities carried at, or permitted to be carried at, fair value are classified within the fair value hierarchy in one of the following categories based on the lowest level input that is significant in measuring fair value: Level 1—Fair value is determined by using unadjusted quoted prices that are available in active markets for identical assets and liabilities. Level 2—Fair value is determined by using inputs other than Level 1 quoted prices that are directly or indirectly observable. Inputs can include quoted prices for similar assets and liabilities in active markets or quoted prices for identical assets and liabilities in inactive markets. Related inputs can also include those used in valuation or other pricing models such as interest rates and yield curves that can be corroborated by observable market data. Level 3—Fair value is determined by using inputs that are unobservable and not corroborated by market data. Use of these inputs involves significant and subjective judgment. We account for certain assets and liabilities at fair value and classify these assets and liabilities within the fair value hierarchy. Our other current assets and other current liabilities have fair values that approximate their carrying values. 5. Fair Value Measurements (Continued) Assets and liabilities subject to fair value measurements are as follows (in millions): As of December 31, 2019 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 270.0 $ — $ — $ 270.0 Time deposits (2) — 87.3 — 87.3 U.S. government and agency securities (3) — 1,227.9 — 1,227.9 Corporate debt securities (3) — 224.1 — 224.1 Equity securities (4) 63.0 — — 63.0 Total assets $ 333.0 $ 1,539.3 $ — $ 1,872.3 Liabilities Contingent consideration (5) — — 13.4 13.4 Total liabilities $ — $ — $ 13.4 $ 13.4 As of December 31, 2018 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 247.6 $ — $ — $ 247.6 Time deposits (2) — 35.9 — 35.9 U.S. government and agency securities (3) — 1,074.2 — 1,074.2 Corporate debt securities (3) — 75.7 — 75.7 Equity securities (4) 3.5 — — 3.5 Total assets $ 251.1 $ 1,185.8 $ — $ 1,436.9 Liabilities Contingent consideration (5) — — 13.4 13.4 Total liabilities $ — $ — $ 13.4 $ 13.4 (1) Included in cash and cash equivalents on our consolidated balance sheets. (2) Included in cash and cash equivalents and current marketable investments on our consolidated balance sheets. The fair value of these securities is principally measured or corroborated by trade data for identical securities in which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (3) Included in cash and cash equivalents and current and non-current marketable investments on our consolidated balance sheets. Refer to Note 4— Investments—Marketable Investments—Available-for-Sale Debt Securities for further information. The fair value of these securities is principally measured or corroborated by trade data for identical securities for which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (4) Included in current marketable investments on our consolidated balance sheets. The fair value of these securities is based on quoted market prices for identical instruments in active markets. During the year ended December 31, 2019, we recognized $21.4 million of net unrealized and realized gains on these securities and recorded these gains on our consolidated statements of operations within other income (expense), net. Refer to Note 4 —Investments — Marketable Investments—Investments in Equity Securities with Readily Determinable Fair Values . 5. Fair Value Measurements (Continued) (5) Included in non-current liabilities on our consolidated balance sheets. The fair value of contingent consideration has been estimated using probability-weighted discounted cash flow models (DCFs). The DCFs incorporate Level 3 inputs including estimated discount rates that we believe market participants would consider relevant in pricing and the projected timing and amount of cash flows, which are estimated and developed, in part, based on the requirements specific to each acquisition agreement. The change in the fair value of contingent consideration for the year ended December 31, 2019 was not material. Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value because of their short maturities. The fair values of our marketable investments and contingent consideration are reported above within the fair value hierarchy. The carrying value of our debt is a reasonable estimate of the fair value of the outstanding debt based on the variable interest rate of the debt.

Accounts Payable and Accrued Ex

Accounts Payable and Accrued Expenses	12 Months Ended
Accounts Payable and Accrued Expenses	Dec. 31, 2019
Accounts Payable and Accrued Expenses
Accounts Payable and Accrued Expenses	6. Accounts Payable and Accrued Expenses Accounts payable and accrued expenses consist of the following by major categories (in millions): As of December 31, 2019 2018 Accounts payable $ 9.9 $ 23.1 Accrued expenses: Sales related (royalties, rebates and fees) 71.5 81.0 Payroll related 43.4 37.9 Other 23.6 24.1 Total accrued expenses $ 138.5 $ 143.0 Total accounts payable and accrued expenses $ 148.4 $ 166.1

Debt

Debt	12 Months Ended
Debt	Dec. 31, 2019
Debt
Debt	7. Debt 2018 Credit Agreement In June 2018, we entered into a credit agreement (the 2018 Credit Agreement) with Wells Fargo Bank, National Association (Wells Fargo), as administrative agent and a swingline lender, and various other lender parties, providing for: (1) an unsecured revolving credit facility of up to $1.0 billion; and (2) a second unsecured revolving credit facility of up to $500.0 million (which facilities may, at our request, be increased by up to $300.0 million in the aggregate subject to obtaining commitments from existing or new lenders for such increase and other conditions). In accordance with the terms of the 2018 Credit Agreement, in June 2019, we extended the maturity date of the 2018 Credit Agreement by one year, to June 2024. The 2018 Credit Agreement provides the lenders the ability to extend the maturity date by one additional year, to June 2025, if we request such an extension. At our option, amounts borrowed under the 2018 Credit Agreement bear interest at either the LIBOR rate or a fluctuating base rate, in each case, plus an applicable margin determined on a quarterly basis based on our consolidated ratio of total indebtedness to EBITDA (as calculated in accordance with the 2018 Credit Agreement). To date, we have elected to calculate interest on the outstanding balance at LIBOR plus an applicable margin. 7. Debt (Continued) On June 27, 2018, we borrowed $250.0 million under the 2018 Credit Agreement, and used the funds to repay outstanding indebtedness under the 2016 Credit Agreement as discussed below under 2016 Credit Agreement On January 24, 2019, we paid $800.0 million under our exclusive license agreement with Arena Pharmaceuticals, Inc. (Arena) and funded the payment by borrowing $800.0 million under the 2018 Credit Agreement. In 2019, we paid down $200.0 million on our revolving credit facility under the 2018 Credit Agreement. This brought our aggregate outstanding balance under the 2018 Credit Agreement to $850.0 million as of December 31, 2019. Although our credit facility matures in 2024, we classified $250.0 million of the outstanding balance as a current liability on our consolidated balance sheet as of December 31, 2019 as we intend to repay this amount within one year. The 2018 Credit Agreement contains customary events of default and customary affirmative and negative covenants. As of December 31, 2019, we were in compliance with these covenants. Lung Biotechnology PBC is our only subsidiary that guarantees our obligations under the 2018 Credit Agreement though, from time to time, one or more of our other subsidiaries may be required to guarantee our obligations. In connection with the 2018 Credit Agreement, we capitalized debt issuance costs, which are being amortized to interest expense over the contractual term of the 2018 Credit Agreement. As of December 31, 2019, $3.4 million was recorded in other current assets and $9.3 million in other non-current assets on our consolidated balance sheets. 2016 Credit Agreement In January 2016, we entered into a credit agreement (the 2016 Credit Agreement) with Wells Fargo, as administrative agent and a swingline lender, and various other lender parties, providing for an unsecured revolving credit facility of up to $1.0 billion. On June 1, 2017, we borrowed $250.0 million under this facility and used the funds to initiate an accelerated share repurchase program. Refer to Note 10 —Stockholders’ Equity—Share Repurchases. On June 27, 2018, we repaid in full all our obligations under the 2016 Credit Agreement in connection with the termination of the 2016 Credit Agreement and our entry into the 2018 Credit Agreement. There were no penalties associated with the early termination of the 2016 Credit Agreement. Convertible Note Hedge and Warrant Transactions In October 2011, we issued $250.0 million in aggregate principal value 1.0 percent Convertible Senior Notes due September 15, 2016 (Convertible Notes). Upon maturity of the Convertible Notes in September 2016, we fulfilled all remaining settlement and repayment obligations. In connection with the issuance of the Convertible Notes, we sold to Deutsche Bank AG London (DB London) warrants to acquire up to approximately 5.2 million shares of our common stock at a strike price of $67.56 per share. The warrants expired incrementally on a series of expiration dates during December 2016 and January 2017. The warrants were settled on a net-share basis. As the price of our common stock exceeded the strike price of the warrants on each of the series of related incremental expiration dates, we delivered 2.8 million shares of common stock previously held as treasury stock to DB London, including 1.7 million shares that were delivered during the first quarter of 2017. 7. Debt (Continued) Interest Expense Details of interest expense presented on our consolidated statements of operations are as follows (in millions): Year Ended December 31, 2019 2018 2017 Credit Facility interest expense (1) $ 44.2 $ 13.9 $ 7.1 Other interest expense — — 1.9 Total interest expense $ 44.2 $ 13.9 $ 9.0 (1) Represents interest expense related to debt and amortization of issuance costs associated with our 2018 and 2016 Credit Agreements.

Temporary Equity

Temporary Equity	12 Months Ended
Temporary Equity	Dec. 31, 2019
Temporary Equity
Temporary Equity	8. Temporary Equity Temporary equity included certain equity securities that: (1) had redemption features outside our control; (2) were not classified as an asset or liability; (3) were excluded from permanent stockholders’ equity; and (4) were not mandatorily redeemable. Amounts included in temporary equity related to securities that were redeemable at a fixed or determinable price. Components comprising the carrying value of temporary equity include the following (in millions): As of December 31, 2019 2018 Common stock subject to repurchase (1) $ — $ 10.8 Preferred stock with redemption rights (2) — 8.4 Total $ — $ 19.2 (1) Pursuant to a license agreement with Toray Industries Inc. (Toray), we issued 200,000 shares of our common stock (which later split into 400,000 shares) to Toray in 2007, and provided Toray the right to require us to repurchase the shares at a price of $27.21 per share (the Put Right), which resulted in classification of such shares within temporary equity. During the second quarter of 2019, we terminated our license agreement with Toray and the Put Right no longer exists. As a result, upon the termination of the license agreement, we reclassified $10.8 million from temporary equity to additional paid-in capital during the second quarter of 2019. (2) The preferred stock issued by the variable interest entity we previously consolidated includes rights that allow the holders to redeem the preferred stock at the original issuance price in exchange for cash. In the third quarter of 2019, we deconsolidated the entity’s balance sheet, which included $8.4 million of temporary equity. Refer to Note 4 —Investments—Deconsolidation of a Variable Interest Entity for more information.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
Share-Based Compensation	Dec. 31, 2019
Share-Based Compensation
Share-Based Compensation	9. Share-Based Compensation As of December 31, 2019, we have two shareholder-approved equity incentive plans: the United Therapeutics Corporation Amended and Restated Equity Incentive Plan (the 1999 Plan) and the United Therapeutics Corporation Amended and Restated 2015 Stock Incentive Plan (as amended to date, the 2015 Plan). The 2015 Plan provides for the issuance of up to 9,500,000 shares of our common stock pursuant to awards granted under the 2015 Plan, which includes the 450,000 shares added pursuant to an amendment and restatement of the 2015 Plan approved by our shareholders in June 2019. No further awards will be granted under the 1999 Plan. We also have one equity incentive plan, the United Therapeutics Corporation 2019 Inducement Stock Incentive Plan (the 2019 Inducement Plan), that has not been approved by our shareholders, as permitted by the Nasdaq Stock Market rules. The 2019 Inducement Plan was approved by our Board of Directors in February 2019 and provides for the issuance of up to 99,000 shares of our common stock under awards granted to newly-hired employees. Currently, we grant equity-based awards to employees and members of our Board of Directors in the form of stock options and restricted stock units under the 2015 Plan, and we grant restricted stock units to newly-hired employees under the 2019 Inducement Plan. Refer to the sections entitled Stock Options Restricted Stock Units We previously issued awards under the United Therapeutics Corporation Share Tracking Awards Plan (2008 STAP) and the United Therapeutics Corporation 2011 Share Tracking Awards Plan (2011 STAP). We refer to the 2008 STAP and the 2011 STAP collectively as the “STAP” and awards outstanding under either of these plans as “STAP awards.” Refer to the section entitled Share Tracking Awards Plans In 2012, our shareholders approved the United Therapeutics Corporation Employee Stock Purchase Plan (ESPP), which is structured to comply with Section 423 of the Internal Revenue Code. Refer to the section entitled Employee Stock Purchase Plan The following table reflects the components of share-based compensation expense (benefit) recognized in our consolidated statements of operations (in millions): Year Ended December 31, 2019 2018 2017 Stock options $ 70.5 $ 58.5 $ 43.0 Restricted stock units 13.3 7.3 2.2 STAP awards (39.7) (93.4) 27.1 Employee stock purchase plan 1.3 1.2 1.2 Total share-based compensation expense (benefit) before tax $ 45.4 $ (26.4) $ 73.5 Share-based compensation capitalized as part of inventory $ 0.7 $ 0.7 $ 0.4 As a result of the adoption of ASU 2016-09, we established an accounting policy election to account for forfeitures of share-based awards and STAPs when they occur. Upon adoption, we recognized a cumulative-effect adjustment for the removal of the forfeiture estimate with respect to awards that were continuing to vest as of January 1, 2017. The adjustment decreased retained earnings by $5.8 million, net of tax. 9. Share-Based Compensation (Continued) Stock Options We estimate the fair value of stock options using the Black-Scholes-Merton valuation model, which requires us to make certain assumptions that can materially impact the estimation of fair value and related compensation expense. The assumptions used to estimate fair value include the price of our common stock, the expected volatility of our common stock, the risk-free interest rate, the expected term of stock option awards and the expected dividend yield. In March 2017 and March 2018, we issued stock options with performance conditions to certain executives with vesting conditions tied to the achievement of specified performance criteria, which have target performance levels that span from one A description of the key inputs, requiring estimates, used in determining the fair value of stock options are provided below: Expected term Share Tracking Awards Plans Expected volatility Risk-free interest rate Expected dividend yield The following weighted average assumptions were used in estimating the fair value of stock options granted to employees during the twelve months ended December 31, 2019, December 31, 2018, and December 31, 2017: Year Ended December 31, 2019 2018 2017 Expected term of awards (in years) 5.8 6.3 6.1 Expected volatility 33.8 % 36.2 % 35.7 % Risk-free interest rate 2.4 % 2.7 % 2.2 % Expected dividend yield 0.0 % 0.0 % 0.0 % 9. Share-Based Compensation (Continued) A summary of the activity and status of stock options under our equity incentive plans is presented below: Weighted Average Weighted Remaining Aggregate Average Contractual Intrinsic Exercise Term Value Options Price (in Years) (in millions) Outstanding at January 1, 2019 6,299,803 $ 120.78 Granted 2,081,047 124.87 Exercised (191,508) 51.53 Forfeited (100,662) 131.11 Outstanding at December 31, 2019 8,088,680 $ 123.34 6.3 $ 12.7 Exercisable at December 31, 2019 3,928,404 $ 119.45 5.1 $ 11.9 Unvested at December 31, 2019 4,160,276 $ 127.02 7.4 $ 0.8 The weighted average fair value of a stock option granted during each of the years in the three-year period ended December 31, 2019, was $39.63, $45.01 and $56.07, respectively. The total fair value of stock options that vested for each of the years in the three-year period ended December 31, 2019, was $37.4 million, $33.9 million and $13.1 million, respectively. Total share-based compensation expense related to stock options is recorded as follows (in millions): Year Ended December 31, 2019 2018 2017 Cost of product sales $ 0.8 $ 0.9 $ 1.3 Research and development 3.7 3.7 3.7 Selling, general and administrative 66.0 53.9 38.0 Share-based compensation expense before tax 70.5 58.5 43.0 Related income tax benefit (16.0) (13.3) (15.8) Share-based compensation expense, net of tax $ 54.5 $ 45.2 $ 27.2 As of December 31, 2019, unrecognized compensation cost relating to stock options was $90.1 million. Unvested outstanding stock options as of December 31, 2019 had a weighted average remaining vesting period of 2.5 years. Stock option exercise data is summarized below (dollars in millions): Year Ended December 31, 2019 2018 2017 Number of options exercised 191,508 289,393 461,465 Cash received from options exercised $ 9.9 $ 15.6 $ 39.9 Total intrinsic value of options exercised $ 11.5 $ 17.0 $ 29.3 Tax benefits realized from options exercised (1) $ 2.6 $ 3.9 $ 10.6 (1) We recognize these tax benefits on our consolidated statements of operations within income tax benefit (expense). 9. Share-Based Compensation (Continued) Restricted Stock Units In June 2016, we began issuing restricted stock units to our non-employee directors. In October 2017, we also began issuing restricted stock units to our employees. Each restricted stock unit entitles the recipient to one share of our common stock upon vesting. We measure the fair value of restricted stock units using the stock price on the date of grant. Share-based compensation expense for the restricted stock units is recorded ratably over their vesting period. A summary of the activity with respect to, and status of, restricted stock units during year ended December 31, 2019 is presented below: Weighted Average Weighted Remaining Aggregate Number of Average Contractual Intrinsic Restricted Grant Term Value Stock Units Price (in Years) (in millions) Unvested at January 1, 2019 186,255 $ 112.48 Granted 225,218 112.69 Vested (74,324) 111.94 Forfeited/canceled (26,424) 118.62 Unvested at December 31, 2019 310,725 $ 112.24 8.9 $ 27.4 Total share-based compensation expense relating to restricted stock units is recorded as follows (in millions): Year Ended December 31, 2019 2018 2017 Cost of product sales $ 1.0 $ 0.5 $ — Research and development 4.4 1.7 — Selling, general and administrative 7.9 5.1 2.2 Share-based compensation expense before tax 13.3 7.3 2.2 Related income tax benefit (3.0) (1.7) (0.8) Share-based compensation expense, net of tax $ 10.3 $ 5.6 $ 1.4 As of December 31, 2019, unrecognized compensation cost related to the grant of restricted stock units was $24.1 million. Unvested outstanding restricted stock units as of December 31, 2019 had a weighted average remaining vesting period of 1.9 years. Share Tracking Awards Plans STAP awards convey the right to receive in cash an amount equal to the appreciation of our common stock, which is measured as the increase in the closing price of our common stock between the dates of grant and exercise. STAP awards expire on the tenth anniversary of the grant date, and in most cases they vest in equal increments on each anniversary of the grant date over a four-year period. The aggregate STAP liability balance was $25.0 million and $72.2 million at December 31, 2019 and 2018, respectively, all of which was classified as a current liability on our consolidated balance sheets. 9. Share-Based Compensation (Continued) Estimating the fair value of STAP awards requires the use of certain inputs that can materially impact the determination of fair value and the amount of compensation expense (benefit) we recognize. Inputs used in estimating fair value include the price of our common stock, the expected volatility of the price of our common stock, the risk-free interest rate, the expected term of STAP awards, and the expected dividend yield. The fair value of the STAP awards is measured at the end of each financial reporting period because the awards are settled in cash. Refer to the descriptions of these key inputs, requiring estimates, used in determining the fair value of the awards in the Stock Options Expected term The table below includes the weighted-average assumptions used to measure the fair value of the outstanding STAP awards: As of December 31, 2019 2018 2017 Expected term of awards (in years) 2.0 2.5 1.8 Expected volatility 29.1 % 30.9 % 31.7 % Risk-free interest rate 1.6 % 2.5 % 1.8 % Expected dividend yield 0.0 % 0.0 % 0.0 % The closing price of our common stock was $88.08, $108.90, and $147.95 on December 31, 2019, 2018 and 2017, respectively. 9. Share-Based Compensation (Continued) A summary of the activity and status of STAP awards during the year ended December 31, 2019 is presented below: Weighted Average Weighted- Remaining Aggregate Average Contractual Intrinsic Number of Exercise Term Value Awards Price (Years) (in millions) Outstanding at January 1, 2019 2,867,979 $ 107.85 Granted — — Exercised (156,876) 59.05 Forfeited (88,775) 157.26 Outstanding at December 31, 2019 2,622,328 $ 109.10 4.1 $ 29.9 Exercisable at December 31, 2019 2,612,328 $ 109.32 4.1 $ 29.5 Unvested at December 31, 2019 10,000 $ 52.57 2.9 $ 0.4 Share-based compensation (benefit) expense recognized in connection with STAP awards is as follows (in millions): Year Ended December 31, 2019 2018 2017 Cost of product sales $ (1.7) $ (4.7) $ 1.2 Research and development (8.2) (17.9) 4.1 Selling, general and administrative (29.8) (70.8) 21.8 Share-based compensation (benefit) expense before tax (39.7) (93.4) 27.1 Related income tax expense (benefit) 9.0 21.3 (10.0) Share-based compensation (benefit) expense, net of tax $ (30.7) $ (72.1) $ 17.1 Cash paid to settle STAP exercises during the years ended December 31, 2019, 2018 and 2017 was $7.6 million, $75.7 million, and $63.4 million, respectively. Employee Stock Purchase Plan In June 2012, our shareholders approved the ESPP, which is structured to comply with Section 423 of the Internal Revenue Code. The ESPP provides eligible employees with the right to purchase shares of our common stock at a discount through elective accumulated payroll deductions at the end of each offering period. Offering periods, which began in 2012, occur in consecutive six-month periods commencing on September 5th and March 5th of each year. Eligible employees may contribute up to 15 percent of their base salary, subject to certain annual limitations as defined in the ESPP. The purchase price of the shares is equal to the lower of 85 percent of the closing price of our common stock on either the first or last trading day of a given offering period. In addition, the ESPP provides that no eligible employee may purchase more than 4,000 shares during any offering period. The ESPP has a 20-year term and limits the aggregate number of shares that can be issued under the ESPP to 3.0 million.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
Stockholders' Equity	Dec. 31, 2019
Stockholders' Equity
Stockholders' Equity	10. Stockholders’ Equity Earnings Per Common Share Basic (loss) earnings per common share is computed by dividing net (loss) income by the weighted average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the period, adjusted for the potential dilutive effect of our outstanding stock options, restricted stock units and shares issuable under the ESPP, as if they were vested and exercised. For the year ended December 31, 2019, we had a net loss, and as such, all outstanding stock options, restricted stock units and shares issuable under the ESPP were excluded from our calculation of diluted loss per share. The components of basic and diluted (loss) earnings per common share comprised the following (in millions, except per share amounts): Year Ended December 31, 2019 2018 2017 Numerator: Net (loss) income $ (104.5) $ 589.2 $ 417.9 Denominator: Weighted average outstanding shares—basic 43.8 43.5 44.0 Effect of dilutive securities (1) : Warrants — — 0.1 Stock options, restricted stock units and employee stock purchase plan — 0.5 0.8 Weighted average shares—diluted (2) 43.8 44.0 44.9 Net (loss) income per common share: Basic $ (2.39) $ 13.54 $ 9.50 Diluted $ (2.39) $ 13.39 $ 9.31 Stock options, restricted stock units, shares issuable under the ESPP and warrants excluded from calculation (2) 7.2 4.7 3.3 (1) Calculated using the treasury stock method. (2) Certain stock options, restricted stock units, shares issuable under the ESPP and warrants have been excluded from the computation of diluted (loss) earnings per share because their impact would be anti-dilutive. Share Repurchases In April 2017, our Board of Directors approved a share repurchase program authorizing up to $250.0 million in aggregate repurchases of our common stock. Pursuant to this authorization, in May 2017, we paid $250.0 million to enter into an accelerated share repurchase agreement (ASR) with Citibank, N.A. (Citibank). Pursuant to the terms of the ASR, in June 2017, Citibank delivered to us approximately 1.7 million shares of our common stock, representing the minimum number of shares we were entitled to receive under the ASR. Upon termination of the ASR in September 2017, Citibank delivered to us approximately 0.3 million additional shares of our common stock. The ASR was accounted for as an equity transaction and the shares we repurchased under the ASR were included in treasury stock when the shares were received. 10. Stockholders’ Equity (Continued) Shareholder Rights Plan In June 2008, we entered into an Amended and Restated Rights Agreement with The Bank of New York as Rights Agent (the Plan), which amended and restated our original Rights Agreement dated December 17, 2000. The Plan, as amended and restated, extended the expiration date of the Preferred Share Purchase Rights (Rights) from December 29, 2010 to June 26, 2018, and increased the purchase price of each Right from $64.75 to $400.00, respectively. Each Right entitled holders to purchase one one-thousandth of a share of our Series A Junior Participating Preferred Stock. Rights were exercisable only upon our acquisition by another company, or commencement of a tender offer that would result in ownership of 15 percent or more of the outstanding shares of our voting stock by a person or group (as defined under the Plan) without our prior express written consent. The Plan expired on June 26, 2018 in accordance with its terms. As of December 31, 2019, we have not issued any shares of our Series A Preferred Stock. Accumulated Other Comprehensive Loss The following table includes changes in accumulated other comprehensive loss by component, net of tax (in millions): Unrealized Gains and Defined Foreign (Losses) on Benefit Currency Available-for- Pension Translation Sale Plan (1) Losses Securities Total Balance, January 1, 2019 $ 12.3 $ (17.9) $ (2.3) $ (7.9) Other comprehensive (loss) income before reclassifications (10.6) — 6.0 (4.6) Amounts reclassified from accumulated other comprehensive loss (1.7) — — (1.7) Net current-period other comprehensive (loss) income (12.3) — 6.0 (6.3) Balance, December 31, 2019 $ — $ (17.9) $ 3.7 $ (14.2) Unrealized Gains and Defined Foreign (Losses) on Benefit Currency Available-for- Pension Translation Sale Plan (1) Losses Securities Total Balance, January 1, 2018 $ 0.2 $ (17.9) $ (1.9) $ (19.6) Other comprehensive income (loss) before reclassifications 10.7 — (0.4) 10.3 Amounts reclassified from accumulated other comprehensive loss 1.4 — — 1.4 Net current-period other comprehensive income (loss) 12.1 — (0.4) 11.7 Balance, December 31, 2018 $ 12.3 $ (17.9) $ (2.3) $ (7.9) (1) Refer to Note 12— Employee Benefit Plans — Supplemental Executive Retirement Plan , which identifies the captions within our consolidated statements of operations where reclassification adjustments were recognized and their associated tax impact.

Income Taxes

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2019
Income Taxes
Income Taxes	11. Income Taxes Components of income tax (benefit) expense consist of the following (in millions): Year Ended December 31, 2019 2018 2017 Current: Federal $ 63.1 $ 136.6 $ 261.3 State 9.4 17.4 23.9 Total current 72.5 154.0 285.2 Deferred Federal (120.1) 12.7 67.2 State (12.9) 3.0 (0.8) Total deferred (133.0) 15.7 66.4 Total income tax (benefit) expense $ (60.5) $ 169.7 $ 351.6 Presented below is a reconciliation of income tax (benefit) expense computed at the statutory federal tax rate of 21 percent in 2019 and 2018, and 35 percent in 2017 to income tax (benefit) expense as reported (in millions): Year Ended December 31, 2019 2018 2017 Federal taxes at the statutory rate $ (34.7) $ 159.4 $ 269.2 General business credits (20.4) (14.9) (15.1) Nondeductible compensation expense 6.3 2.1 1.8 Change in valuation allowance (5.7) 11.2 17.5 Foreign income adjustment 5.1 — — State taxes, net of federal benefit (4.0) 15.3 14.2 Deduction for foreign-derived intangible income (3.3) (3.3) — Deconsolidation of VIE (1.9) — — Other (1.6) 3.6 1.3 Excess tax benefits from share-based compensation (0.3) (1.9) (4.5) Tax reform — (1.8) 71.0 Section 199 deduction — — (22.8) Nondeductible portion of DOJ Settlement — — 19.0 Total income tax (benefit) expense $ (60.5) $ 169.7 $ 351.6 11. Income Taxes (Continued) Components of the net deferred tax assets are as follows (in millions): As of December 31, 2019 2018 Deferred tax assets: Intangible assets $ 192.4 $ 36.5 Share-based compensation 56.0 57.0 Impairments 25.8 23.1 SERP 10.1 10.7 NOLs 6.7 34.3 Reserves 6.5 9.3 Other 14.6 20.7 Total deferred tax assets 312.1 191.6 Deferred tax liabilities: Plant and equipment principally due to differences in depreciation (40.7) (20.2) Basis differences in foreign entities 0.6 (24.8) Other (5.4) (8.3) Net deferred tax assets before valuation allowance 266.6 138.3 Valuation allowance (36.6) (42.6) Net deferred tax assets $ 230.0 $ 95.7 As of December 31, 2019, there were no unrecognized tax benefits. As of December 31, 2018, there were $0.5 million of unrecognized tax benefits, which included $0.3 million of tax benefits that, if recognized, would impact our effective income tax rate (ETR). We record interest and penalties related to uncertain tax positions as a component of income tax expense. As of December 31, 2019 and 2018, we have not accrued any material interest expense related to uncertain tax positions. We are unaware of any material positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly increase or decrease within the next twelve months. The Global Intangible Low Tax Income (GILTI) provision of Tax Reform requires us to include in our U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. We have elected to account for the GILTI tax in the period in which it is incurred, and do not expect any significant impacts from this tax. We are subject to federal and state taxation in the United States and various foreign jurisdictions. We are no longer subject to income tax examinations by the Internal Revenue Service and all other major jurisdictions for tax years prior to 2011. At December 31, 2019, we have gross federal, foreign and state net operating loss carryforwards of $9.2 million, $9.9 million and $86.1 million, respectively, which will either expire at various dates beginning in 2031 or have no expiration date. We expect that a significant amount of these carryforwards will expire unused, so we have established valuation allowances for the related deferred tax assets. Certain of our investments in privately-held companies have been impaired and have associated deferred tax assets. We have established valuation allowances for most of the deferred tax assets related to the impairments due to their capital nature, which makes them unlikely to be recognized.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2019
Employee Benefit Plans
Employee Benefit Plans	12. Employee Benefit Plans Supplemental Executive Retirement Plan We maintain the United Therapeutics Corporation Supplemental Executive Retirement Plan (SERP) to provide retirement benefits to certain senior members of our management team. Participants who retire at age 60 or older are eligible to receive either monthly payments or a lump sum payment based on an average of their total gross base salary over the last 36 months of active employment, subject to certain adjustments. Related benefit payments commence on the first day of the six Because we do not fund the SERP, we recognize a liability equal to the projected benefit obligation as measured at the end of each fiscal year. A reconciliation of the beginning and ending balances of the projected benefit obligation is presented below (in millions): Year Ended December 31, 2019 2018 Projected benefit obligation at the beginning of the year $ 46.8 $ 55.9 Service cost 2.2 2.4 Interest cost 1.4 1.6 Benefits paid (5.1) (0.2) Net actuarial loss (gain) (1) 10.8 (12.9) Projected benefit obligation at the end of the year $ 56.1 $ 46.8 Amount included in Other current liabilities (2) $ 17.5 $ 19.9 Amount included in Other non-current liabilities $ 38.6 $ 26.9 (1) During the fourth quarter of 2018, a participant in the SERP departed before retirement age under the terms of the SERP. As a result, we recorded a $7.0 million reduction to the benefit obligation as of December 31, 2018. (2) This amount represents the benefit obligation due to participants who are eligible to retire and whose benefit payments could commence within one year of the respective balance sheet date. The following weighted average assumptions were used to measure the SERP obligation: Year Ended December 31, 2019 2018 Discount rate 2.63 % 3.92 % Salary increases 4.00 % 4.00 % Lump-sum distribution rate 3.00 % 4.50 % 12. Employee Benefit Plans (Continued) The components of net periodic pension cost recognized on our consolidated statements of operations consisted of the following (in millions): Year Ended December 31, 2019 2018 2017 Service cost $ 2.2 $ 2.4 $ 2.2 Interest cost 1.4 1.6 1.6 Amortization of prior service cost 1.5 1.5 1.5 Amortization of net actuarial gain (2.2) (0.2) (0.6) Settlement (1.9) — — Total $ 1.0 $ 5.3 $ 4.7 For the years ended December 31, 2019 and December 31, 2018, the service cost component is reported within Operating expenses and the other components are reported in other income (expense), net on our consolidated statements of operations. For the year ended December 31, 2017, all components of net periodic pension cost are reported within Operating expenses on our consolidated statements of operations. We did not reclassify amounts for the year ended December 31, 2017 to conform with current year presentation as these amounts were not material to our financial statements. Amounts related to the SERP that have been recognized in other comprehensive (loss) income are as follows (in millions): Year Ended December 31, 2019 2018 2017 Net actuarial (loss) gain $ (12.9) $ 12.7 $ (3.2) Prior service cost 1.5 1.5 1.5 Settlement (1.9) — — Total recognized in other comprehensive (loss) income (13.3) 14.2 (1.7) Tax benefit (expense) 1.0 (2.1) 0.6 Total, net of tax $ (12.3) $ 12.1 $ (1.1) The table below presents amounts related to the SERP included in accumulated other comprehensive loss that have not yet been recognized as a component of net periodic pension cost on our consolidated statements of operations (in millions): Year Ended December 31, 2019 2018 2017 Net actuarial gain $ (4.5) $ (19.3) $ (6.6) Prior service cost 3.3 4.7 6.2 Total included in accumulated other comprehensive loss (1.2) (14.6) (0.4) Tax expense 1.2 2.3 0.2 Total, net of tax $ — $ (12.3) $ (0.2) 12. Employee Benefit Plans (Continued) We estimate $1.3 million of the prior service cost included in accumulated other comprehensive loss as of December 31, 2019 will be recognized as a component of net periodic pension cost on our consolidated statements of operations for the year ended December 31, 2020. The accumulated benefit obligation, a measure that does not consider future increases in participants’ salaries, was $47.4 million and $39.8 million at December 31, 2019 and 2018, respectively. Future estimated benefit payments, based on current assumptions, including election of lump-sum distributions and expected future service, are as follows (in millions): Year Ended December 31, 2020 $ 17.5 2021 — 2022 — 2023 6.2 2024 16.1 Thereafter 44.8 Total $ 84.6 Employee Retirement Plan We maintain a Section 401(k) Salary Reduction Plan which is open to all eligible full-time employees. Under the 401(k) Plan, eligible employees can make pre-tax or after-tax contributions up to statutory limits. Currently, we make discretionary matching contributions to the 401(k) Plan equal to 40 percent of a participant’s elected salary deferral. Matching contributions vest immediately for participants who have been employed for three years; otherwise, matching contributions vest annually, in one-third

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2019
Commitments and Contingencies
Commitments and Contingencies	13. Commitments and Contingencies Operating Leases We lease facilities and equipment under operating lease arrangements that have terms expiring at various dates through 2028. Certain lease arrangements include renewal options and escalation clauses. In addition, various lease agreements to which we are party require that we comply with certain customary covenants throughout the term of these leases. If we are unable to comply with these covenants and cannot reach a satisfactory resolution in the event of noncompliance, these agreements could terminate. 13. Commitments and Contingencies (Continued) Future minimum lease payments under non-cancelable operating leases as of December 31, 2019, are as follows (in millions): Year Ending December 31, 2020 $ 2.1 2021 1.7 2022 1.0 2023 0.7 2024 0.4 Thereafter 0.6 Total $ 6.5 Total rent expense was $4.9 million, $4.2 million and $4.8 million for the years ended December 31, 2019, 2018 and 2017, respectively. The amounts recorded in operating lease expense include short-term leases and variable lease costs, which are immaterial. 13. Commitments and Contingencies (Continued) Milestone Payments and Royalty Obligations We are party to certain license agreements pursuant to which we have in-licensed or acquired intellectual property rights covering our commercial and/or development-stage products. Generally, these agreements require that we make milestone payments in cash upon the achievement of certain product development and commercialization goals and payments of royalties upon commercial sales. The following table outlines our financial obligations under certain of these agreements: Counterparty Relevant Product Our Financial Obligation Supernus Pharmaceuticals, Inc. Orenitram Single-digit Lilly Adcirca Five percent royalty on net product sales of Adcirca through November 2017; from December 1, 2017 through December 31, 2020, ten percent royalty on net sales, plus milestone payments of $325,000 for each $1,000,000 in net product sales The Scripps Research Institute Unituxin One percent royalty on net product sales of Unituxin Medtronic, Inc. Implantable System for Remodulin Ten percent royalty on net product sales of Remodulin delivered via the Implantable System for Remodulin. Reimbursement of Medtronic’s development costs and costs incurred in providing commercialization support DEKA Research & Development Corp. Remunity Product fees and single-digit Samumed LLC LNG01 (formerly SM04646) Low double-digit royalties on LNG01 net product sales and up to $340.0 million in developmental milestone payments 13. Commitments and Contingencies (Continued) Counterparty Relevant Product Our Financial Obligation MannKind Corporation Treprostinil Technosphere Low double-digit royalties on net product sales of Treprostinil Technosphere and up to $50.0 million in developmental milestone payments (of which $25.0 million have already been paid) Arena Ralinepag Low double-digit, tiered royalties on net product sales of ralinepag (any route of administration); a one-time payment of $250.0 million upon FDA approval of an inhaled formulation of ralinepag to treat PAH; and a one-time payment of $150.0 million upon approval in certain non-US jurisdictions of an oral version of ralinepag to treat any indication

Segment Information

Segment Information	12 Months Ended
Segment Information	Dec. 31, 2019
Segment Information
Segment Information	14. Segment Information We currently operate as one operating segment with a focus on the development and commercialization of products to address the unmet needs of patients with chronic and life-threatening conditions. Our Chief Executive Officer, as our chief operating decision maker, manages and allocates resources to the operations of our company on a consolidated basis. This enables our Chief Executive Officer to assess our overall level of available resources and determine how best to deploy these resources across functions, therapeutic areas, and research and development projects in line with our long-term company-wide strategic goals. Net product sales, cost of product sales and gross profit for each of our commercial products were as follows (in millions): Remodulin Tyvaso Orenitram Unituxin Adcirca Total Year Ended December 31, 2019 Net product sales $ 587.0 $ 415.6 $ 225.3 $ 113.7 $ 107.2 $ 1,448.8 Cost of product sales 21.1 19.6 15.0 15.7 46.2 117.6 Gross profit $ 565.9 $ 396.0 $ 210.3 $ 98.0 $ 61.0 $ 1,331.2 Year Ended December 31, 2018 Net product sales $ 599.0 $ 415.2 $ 205.1 $ 84.8 $ 323.7 $ 1,627.8 Cost of product sales 14.1 17.3 13.2 14.3 139.8 198.7 Gross profit $ 584.9 $ 397.9 $ 191.9 $ 70.5 $ 183.9 $ 1,429.1 Year Ended December 31, 2017 Net product sales $ 670.9 $ 372.9 $ 185.8 $ 76.0 $ 419.7 $ 1,725.3 Cost of product sales 15.9 18.5 15.3 12.9 43.1 105.7 Gross profit $ 655.0 $ 354.4 $ 170.5 $ 63.1 $ 376.6 $ 1,619.6 14. Segment Information (Continued) Geographic revenues are determined based on the country in which our customers (distributors) are located. Total revenues from external customers by geographic area are as follows (in millions): Year Ended December 31, 2019 2018 2017 United States $ 1,323.2 $ 1,528.2 $ 1,536.8 Rest-of-World (1) 125.6 99.6 188.5 Total $ 1,448.8 $ 1,627.8 $ 1,725.3 (1) Primarily Europe. We recorded revenue from two distributors in the United States that exceeded 10 percent of total revenues. Revenue from these two distributors as a percentage of total revenues is as follows: Year Ended December 31, 2019 2018 2017 Distributor 1 54 % 51 % 46 % Distributor 2 22 % 18 % 15 % Long-lived assets (property, plant and equipment) located by geographic area are as follows (in millions): Year Ended December 31, 2019 2018 2017 United States $ 723.1 $ 684.0 $ 544.5 Rest-of-World 15.4 15.7 1.2 Total $ 738.5 $ 699.7 $ 545.7

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
Quarterly Financial Information (Unaudited)	Dec. 31, 2019
Quarterly Financial Information (Unaudited)
Quarterly Financial Information (Unaudited)	15. Quarterly Financial Information (Unaudited) Summarized quarterly financial information for each of the years ended December 31, 2019 and 2018 are as follows (in millions, except per share amounts): Quarter Ended December 31, September 30, June 30, March 31, 2019 2019 2019 2019 Total revenues $ 311.1 $ 401.5 $ 373.6 $ 362.6 Cost of product sales 28.8 33.0 26.7 29.1 Gross profit 282.3 368.5 346.9 333.5 Net income (loss) (1) 52.6 132.4 205.1 (494.6) Net income (loss) per share—basic $ 1.20 $ 3.02 $ 4.68 $ (11.32) Net income (loss) per share—diluted $ 1.20 $ 3.01 $ 4.66 $ (11.32) 15. Quarterly Financial Information (Unaudited) (Continued) Quarter Ended December 31, September 30, June 30, March 31, 2018 2018 2018 2018 Total revenues $ 381.4 $ 412.7 $ 444.5 $ 389.2 Cost of product sales 31.9 51.9 61.7 53.2 Gross profit 349.5 360.8 382.8 336.0 Net income (2) 65.3 106.5 172.9 244.5 Net income per share—basic $ 1.50 $ 2.44 $ 4.01 $ 5.65 Net income per share—diluted $ 1.48 $ 2.42 $ 3.98 $ 5.57 (1) Operating results for the quarters ended December 31, 2019, September 30, 2019, June 30, 2019 and March 31, 2019 included $5.6 million, $1.2 million, $(46.0) million and $8.5 million, net of tax, for STAP related share-based compensation expense (benefit), respectively. (2) Operating results for the quarters ended December 31, 2018, September 30, 2018, June 30, 2018 and March 31, 2018 included $(10.3) million, $24.8 million, $2.1 million and $(88.7) million, net of tax, for STAP related share-based compensation (benefit) expense, respectively.

Litigation

Litigation	12 Months Ended
Litigation	Dec. 31, 2019
Litigation
Litigation	16. Litigation Department of Justice Subpoena In May 2016, we received a subpoena from the U.S. Department of Justice (DOJ) requesting documents regarding our support of 501(c)(3) organizations that provide financial assistance to patients. Other companies received similar inquiries as part of a DOJ investigation regarding whether that support may violate the Federal Anti-Kickback Statute and the Federal False Claims Act. On December 19, 2017, we entered into a civil Settlement Agreement with the DOJ and the Office of Inspector General (OIG) of the Department of Health and Human Services (collectively the “United States Government”). The Settlement Agreement is neither an admission of facts nor liability, nor a concession by the United States Government that its contentions are not well-founded. Under the Settlement Agreement, we paid to the United States Government the sum of approximately $210.0 million. During 2017, we recorded a $210.0 million accrual related to this matter. In connection with the civil settlement, we also entered into a Corporate Integrity Agreement with the OIG, effective as of December 18, 2017, which requires us to maintain our corporate compliance program and to undertake a set of defined corporate integrity obligations for a period of five years , ending in December 2022. 16. Litigation (Continued) Sandoz and RareGen, LLC On April 16, 2019, Sandoz Inc. (Sandoz) and its commercialization collaborator, RareGen, LLC, filed a complaint in the U.S. District Court for the District of New Jersey against us and Smiths Medical ASD, Inc. (Smiths Medical), alleging that we and Smiths Medical engaged in anticompetitive conduct in connection with plaintiffs’ efforts to launch their generic version of Remodulin. In particular, the complaint alleges that we and Smiths Medical unlawfully impeded competition by entering into an agreement to produce CADD-MS ®

Arena License Agreement

Arena License Agreement	12 Months Ended
Arena License Agreement	Dec. 31, 2019
Arena License Agreement
Arena License Agreement	17. Arena License Agreement On November 15, 2018, we entered into an exclusive license agreement with Arena related to ralinepag, a next-generation, oral, selective and potent prostacyclin receptor agonist being developed for the treatment of PAH. On January 24, 2019, in connection with the closing of the transactions contemplated by the license agreement: (1) Arena granted to us perpetual, irrevocable and exclusive rights throughout the universe to develop, manufacture and commercialize ralinepag; (2) Arena transferred to us certain other assets related to ralinepag, including, among others, related domain names and trademarks, permits, certain contracts, inventory, regulatory documentation, Investigational New Drug (IND) Application No. 109021 (related to ralinepag) and non-clinical, pre-clinical and clinical trial data; (3) we assumed certain limited liabilities from Arena, including, among others, all obligations arising after the closing under the assumed contracts and the IND described above; and (4) we paid Arena an upfront payment of $800.0 million, which was expensed as acquired in-process research and development and included within research and development expenses on our consolidated statements of operations in the first quarter of 2019. We will also pay Arena: (1) a one-time payment of $250.0 million for the first, if any, marketing approval we receive in the United States for an inhaled version of ralinepag to treat PAH; (2) a one-time payment of $150.0 million for the first, if any, marketing approval we receive in any of Japan, France, Italy, the United Kingdom, Spain or Germany for an oral version of ralinepag to treat any indication; and (3) low double-digit, tiered royalties on net sales of any pharmaceutical product containing ralinepag as an active ingredient, subject to certain adjustments for third party license payments.

Schedule II-Valuation and Quali

Schedule II-Valuation and Qualifying Accounts	12 Months Ended
Schedule II-Valuation and Qualifying Accounts	Dec. 31, 2019
Schedule II-Valuation and Qualifying Accounts
Schedule II-Valuation and Qualifying Accounts	United Therapeutics Corporation Schedule II—Valuation and Qualifying Accounts Years Ended December 31, 2019, 2018 and 2017 (In millions) Valuation Allowance on Deferred Tax Assets Balance at Additions Beginning Charged to Other Balance at of Year Expense Additions Deductions End of Year Year Ended December 31, 2019 (1) $ 42.6 $ 1.9 $ 0.9 $ (8.8) $ 36.6 Year Ended December 31, 2018 (2) $ 16.9 $ 14.9 $ 11.0 $ (0.2) $ 42.6 Year Ended December 31, 2017 (3) $ 4.7 $ 11.8 $ 1.6 $ (1.2) $ 16.9 (1) Other Additions consists of changes related to our investment in a foreign entity. (2) Other Additions consists of valuation allowances related to the acquisition of SteadyMed, SteadyMed dual consolidated loss limitation, and changes in deferred taxes related to our investment in a variable interest entity that were not charged to expense. (3) Other Additions consists of valuation allowances related to our investment in a variable interest entity. Inventory Reserves Balance at Additions Beginning Charged to Balance at of Year Expense Deductions End of Year Year Ended December 31, 2019 $ 26.0 $ 8.4 $ (13.5) $ 20.9 Year Ended December 31, 2018 $ 25.1 $ 11.7 $ (10.8) $ 26.0 Year Ended December 31, 2017 $ 17.5 $ 12.1 $ (4.5) $ 25.1

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2019
Summary of Significant Accounting Policies
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements of United Therapeutics Corporation and its consolidated subsidiaries have been prepared in accordance with accounting principles generally accepted in the United States (GAAP). All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of our consolidated financial statements in accordance with GAAP requires our management to make estimates and assumptions that affect reported amounts of assets and liabilities at the date of our consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. We base our estimates on assumptions regarding historical experience, currently available information and anticipated developments that we believe are reasonable and appropriate. However, because the use of estimates involves an inherent degree of uncertainty, actual results could differ from those estimates. Estimates are used for, but not limited to, revenue recognition, share-based compensation, determining the fair value of assets acquired and liabilities assumed in business combinations, marketable investments, fair value measurements (including those related to contingent consideration), inventory reserves, investments in privately-held companies, income taxes, goodwill and other intangible assets, and obligations related to our Supplemental Executive Retirement Plan.
Fair Value Measurements	Fair Value Measurements Fair value is a market-based measurement, not an entity-specific measurement. The objective of a fair value measurement is to estimate the price to sell an asset or transfer a liability in an orderly transaction between market participants at the measurement date under current market conditions. Such transactions to sell an asset or transfer a liability are assumed to occur in the principal market for that asset or liability, or in the absence of the principal market, the most advantageous market for the asset or liability. 2. Summary of Significant Accounting Policies (Continued) Assets and liabilities subject to fair value measurement disclosures are required to be classified according to a three-level fair value hierarchy with respect to the inputs (or assumptions) used to determine fair value. The level in which an asset or liability is disclosed within the fair value hierarchy is based on the lowest level input that is significant to the related fair value measurement in its entirety. The guidance under the fair value measurement framework applies to other existing accounting guidance in the Financial Accounting Standards Board (FASB) codification that requires or permits fair value measurements. Refer to related disclosures in Note 5— Fair Value Measurements.
Cash Equivalents	Cash Equivalents Cash equivalents consist of highly liquid investments with maturities of three months or less from the date of acquisition.
Marketable Investments	Marketable Investments Our marketable investments are primarily debt securities that we classify as available-for-sale. If we have both the positive intent and the ability to hold the securities until maturity, the securities are classified as held-to-maturity. We determine the appropriate classification of the securities at the time they are acquired and evaluate the appropriateness of such classifications at each balance sheet date. Available-for-sale debt securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive (loss) income in stockholders’ equity, until realized. Held-to-maturity debt securities are recorded at amortized cost, adjusted for the amortization of discounts or premiums. Related discounts and premiums are amortized over the term of these securities as an adjustment to the yield using the effective interest method. Marketable investments are classified as either current or non-current assets on our consolidated balance sheets based on their contractual maturity dates. We monitor our investment portfolio for impairment quarterly or more frequently if circumstances warrant. In the event that the carrying value of a debt security exceeds its fair value and the decline in value is determined to be other-than-temporary, we record an impairment charge within earnings attributable to the estimated credit loss. In determining whether a decline in the value of an investment is other-than-temporary, we evaluate currently available factors that may include, among others: (1) general market conditions; (2) the duration and extent to which fair value has been less than the carrying value; (3) the investment issuer’s financial condition and business outlook; and (4) our assessment as to whether it is more likely than not that we will be required to sell a security prior to recovery of its amortized cost basis.
Inventories	Inventories Inventories are stated at the lower of cost (first-in, first-out method) or net realizable value and consist of the following, net of reserves (in millions): As of December 31, 2019 2018 Raw materials $ 21.1 $ 24.3 Work-in-progress 29.1 28.0 Finished goods 43.2 48.7 Total inventories $ 93.4 $ 101.0
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets The carrying amount of goodwill is not amortized but is subject to annual impairment testing. We conduct our impairment testing of goodwill annually during the fourth quarter, or more frequently if impairment indicators exist. Initially, we evaluate various pertinent qualitative factors to assess whether it is more likely than not that the fair value of a reporting unit to which goodwill has been assigned is less than its carrying value. Such qualitative factors can include, among others: (1) industry and market conditions; (2) present and anticipated sales and cost factors; and (3) overall financial performance. If we conclude based on our qualitative assessment that it is more likely than not that the fair value of a reporting unit is less than its carrying value, we then measure the fair value of the reporting unit and compare its fair value to its carrying value (Step 1 of the goodwill impairment test). If the carrying amount of the reporting unit exceeds its fair value, then the amount of an impairment loss, if any, is measured as the excess of the recorded amount of goodwill over its implied fair value (Step 2 of the goodwill impairment test). We used a qualitative assessment for our goodwill impairment testing for 2019 and 2018. During the year ended December 31, 2019, we wrote off $3.5 million of goodwill related to the deconsolidation of a variable interest entity, as discussed below. There were no impairment losses related to goodwill during the year ended December 31, 2018. Indefinite-lived intangible assets are not amortized but are evaluated annually or more frequently for impairment if impairment indicators exist. Our indefinite-lived intangible assets include purchased in-process research and development (IPR&D) assets, which were measured at their estimated fair values as of their acquisition dates. We used a qualitative assessment for our indefinite-lived intangible asset impairment testing. During the year ended December 31, 2019, we recognized an impairment charge of $8.8 million related to an IPR&D asset associated with our terminated license agreement with the variable interest entity, as discussed below. There were no impairment losses related to indefinite-lived intangible assets during the year ended December 31, 2018. Intangible assets subject to amortization are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an intangible asset may not be recoverable. Impairment losses are measured and recognized to the extent the carrying value of such assets exceeds their fair value. We recorded no impairment losses during the years ended December 31, 2019 and 2018 related to intangible assets subject to amortization. Goodwill and other intangible assets comprise the following (in millions): As of December 31, 2019 As of December 31, 2018 Accumulated Accumulated Gross Amortization Net Gross Amortization Net Goodwill $ 28.0 $ — $ 28.0 $ 31.5 $ — $ 31.5 Other intangible assets: Technology, patents and trade names 6.7 (5.3) 1.4 6.7 (5.1) 1.6 In-process research and development (1) 128.9 — 128.9 137.7 — 137.7 Total $ 163.6 $ (5.3) $ 158.3 $ 175.9 $ (5.1) $ 170.8 (1) In 2018, we determined the fair value of an IPR&D asset resulting from our acquisition of SteadyMed Ltd. using the multi-period earnings method under the income approach. This method reflects the present value of the projected cash flows that are expected to be generated by the IPR&D, less charges representing the required return on other assets to sustain those cash flows. 2. Summary of Significant Accounting Policies (Continued) In June 2019, we elected to terminate our license agreement with the variable interest entity (VIE) discussed under Note 4— Investments—Deconsolidation of a Variable Interest Entity Related amortization expense for the years ended December 31, 2019, 2018 and 2017, was $0.2 million, $0.1 million and $0.5 million, respectively. As of December 31, 2019, aggregate amortization expense related to definite intangible assets each succeeding
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment is recorded at cost and depreciated over its estimated useful life using the straight-line method. The estimated useful lives of property, plant and equipment by major category are as follows: Land improvements 15 Years Buildings 25-39 Years Building improvements 10-39 Years Furniture, equipment and vehicles 3-25 Years Leasehold improvements Remaining lease term, or the estimated useful life of the improvement, whichever is shorter Property, plant and equipment consists of the following (in millions): As of December 31, 2019 2018 Land and land improvements $ 74.4 $ 69.0 Buildings, building improvements and leasehold improvements 573.3 533.3 Buildings under construction 42.0 126.5 Furniture, equipment and vehicles 318.2 205.5 1,007.9 934.3 Less—accumulated depreciation (269.4) (234.6) Property, plant and equipment, net $ 738.5 $ 699.7 Depreciation expense for the years ended December 31, 2019, 2018 and 2017, was $45.7 million, $35.8 million and $30.5 million, respectively. In connection with the completion of construction in the third quarter of 2019 of a building we own, we leased part of the space in the building to another entity as part of a broader collaboration. In 2019, we reclassified $23.7 million of property, plant and equipment, net to other non-current assets on our consolidated balance sheets. For more information, refer to Note 3— Recently Issued Accounting Standards—Accounting Standards Adopted. 2. Summary of Significant Accounting Policies (Continued) Buildings under construction consists of direct costs related to our construction projects.
Investments in Privately-Held Companies	Investments in Privately-Held Companies We measure our non-controlling equity investments in privately-held companies using the measurement alternative because the fair values of these investments are not readily determinable. Under this alternative, the investments are measured at cost, less any impairment, adjusted for any observable price changes. We monitor these investments individually for any observable price changes or impairment indicators. We adjust the measurement of these investments for observable price changes in orderly transactions for the identical or a similar investment of the same issuer. We consider relevant transactions, including any potential funding opportunities, which occur on or before the balance sheet date in evaluating whether any observable price changes have occurred. When a relevant transaction is identified, a careful review of the attendant rights and obligations is necessary to evaluate whether such transaction is deemed to be a similar or identical investment. We include our investments in privately-held companies within other non-current assets on our consolidated balance sheets. These investments are subject to a periodic impairment review and if impaired, the investment is measured and recorded at fair value in accordance with ASC 820, Fair Value Measurements
Treasury Stock	Treasury Stock Repurchased treasury stock is recorded at cost, including commissions and fees. The cost of treasury shares sold or reissued is determined using the first-in, first-out method. Related gains and losses on sales of treasury stock are recognized as adjustments to stockholders’ equity.
Revenue Recognition	Revenue Recognition On January 1, 2018, we adopted Topic 606 using the modified retrospective approach applied to those contracts in effect as of January 1, 2018. Under this transition method, results for reporting periods beginning after January 1, 2018 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported in accordance with our historical accounting under Topic 605, Revenue Recognition To determine revenue recognition for contractual arrangements that we determine are within the scope of Topic 606, we perform the following five steps: (1) identify each contract with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to our performance obligations in the contract; and (5) recognize revenue when (or as) we satisfy the relevant performance obligation. We only apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. 2. Summary of Significant Accounting Policies (Continued) We generate revenues from the sale of our five commercially approved products: Remodulin, Tyvaso, Orenitram, Unituxin and Adcirca. We recognize revenue when we transfer control of our products to our distributors, as our contracts have a single performance obligation (delivery of our product). Except for Adcirca sales, the performance obligation is generally satisfied when our products are delivered to the distributor’s designated location. We recognize revenue from Adcirca sales upon shipment from an Eli Lilly and Company (Lilly) distribution center. Future revenue from delivery of our products will be based on purchase orders provided to us by our distributors. We are not required to disclose the value of unsatisfied performance obligations as our contracts have a non-cancelable duration of one year or less. See Note 14— Segment Information Gross-to-Net Deductions As is customary in the pharmaceutical industry, our product sales are recorded net of various forms of gross-to-net deductions. These deductions vary the consideration to which we are entitled in exchange for the sale of our products to our distributors, and include reserves for: (1) rebates and chargebacks; (2) prompt payment discounts; (3) allowance for sales returns; and (4) distributor fees and other allowances. We estimate these reserves in the same period that we recognize revenue for product sales to distributors. The net product sales amount recognized represents the amount we believe will not be subject to a significant future reversal of revenue. Estimating gross-to-net deductions involves the use of significant assumptions and judgments, as well as information obtained from external sources. For our rebate and chargeback liabilities, in particular, the time lag experienced in the payment of the rebate or chargeback may result in revisions of these accruals in future periods. However, based on our significant history and experience estimating these accruals and our development of these accruals based on the expected value method, we do not believe there will be significant changes to our estimates recorded during the period of sale. We recognized an aggregate $2.3 million decrease in our net product sales for the year ended December 31, 2019 and an aggregate $8.8 million increase in our net product sales for the year ended December 31, 2018, related to revenue recognized from product sales in prior periods. In 2018 we recorded a change in estimate that resulted in the reversal of an estimated liability for Medicaid rebates of $13.6 million, which had initially been recorded in 2017. Additional adjustments to accruals for prior periods primarily related to our participation in state Medicaid programs and contracts with commercial payers. 2. Summary of Significant Accounting Policies (Continued) Rebates and chargebacks. Prompt payment discounts. Product returns. For Unituxin, we ship product with expiration dates that are generally 9 to 14 months after the initial sale. However, our historical returns have not been material and, therefore, we do not record a returns allowance for Unituxin. For sales of our other commercial products, we do not offer our customers a general right of return. 2. Summary of Significant Accounting Policies (Continued) Distributor fees and other allowances. Trade Receivables We invoice and receive payment from our customers after we recognize revenue, resulting in receivables from our customers that are presented as accounts receivable on our consolidated balance sheets. Accounts receivable consist of short-term amounts due from our distributors (generally 30 to 90 days) and are stated at the amount we expect to collect. We establish an allowance for doubtful accounts, if deemed necessary, based on our assessment of the collectability of specific distributor accounts. We did not recognize any impairment losses for accounts receivable for each of the years ended December 31, 2019 and 2018. Changes in accounts receivable are primarily due to the timing and magnitude of orders of our products, the timing of when control of our products is transferred to our distributors and the timing of cash collections. Adcirca Adcirca is manufactured for us by Lilly and distributed through its pharmaceutical wholesaler network on our behalf. Specifically, Lilly handles all of the administrative functions associated with the sale of Adcirca on our behalf, including the receipt and processing of customer purchase orders, shipment to customers, and invoicing and collection of customer payments. We recognize sales of Adcirca on a gross basis (net of reserves for gross-to-net deductions) based on our determination that we are acting as a principal due to our control of the product prior to its transfer to our customers. Our control is evidenced by our substantive ownership of product inventory, the fact that we bear all inventory risks, our primary responsibility for the acceptability of the product to our customers, and our ability to influence net product sales through our contracting decisions with commercial payers and participation in governmental-funded programs.
Research and Development	Research and Development Research and development costs are expensed as incurred except for refundable payments made in advance of services to be provided to us. Related expenses consist of internal labor and overhead, costs to acquire pharmaceutical products and product rights for development, materials used in clinical trials and amounts paid to third parties for services and materials related to drug development and clinical trials. As part of our business strategy, we may in-license the rights to develop and commercialize product candidates. For each in-license transaction, we evaluate whether we have acquired processes or activities along with inputs that would be sufficient to constitute a “business” as defined under GAAP. As defined under GAAP, a “business” consists of inputs and processes applied to those inputs that have the ability to create outputs. Although businesses usually have outputs, outputs are not required for an integrated set of activities to qualify as a business. When we determine that we have not acquired sufficient processes or activities to constitute a business, any up-front payments, as well as pre-commercial milestone payments, are immediately expensed as acquired IPR&D in the period in which they are incurred. Milestone payments made to third parties subsequent to regulatory approval are capitalized as intangible assets and amortized over the estimated remaining useful life of the related product. 2. Summary of Significant Accounting Policies (Continued) We recognize the following costs, among others, as research and development expense in the period related costs are incurred: ● costs associated with in-house or contracted manufacturing activities prior to receiving FDA approval for such facilities, or for major unproven changes to our manufacturing processes; ● costs incurred in-licensing the rights to technologies in the research and development stage that have no alternative future use; and ● up-front payments made in connection with arrangements to obtain license and distribution rights to pharmaceutical product candidates prior to regulatory approval, absent any alternative future use.
Share-Based Compensation	Share-Based Compensation Generally, the fair value of a stock option grant is measured on its grant date and related compensation expense is recognized ratably over the requisite service period. We issue new shares of our common stock upon the exercise of stock options. Additionally, certain executives have stock options with performance conditions that have vesting rights tied to achievement of specific targeted criteria. Share-based compensation expense for all awards is recorded ratably over their vesting period, depending on the specific terms of the award and achievement of the specified performance conditions. Refer to Note 9— Share-Based Compensation We measure the fair value of restricted stock units using the stock price on the date of grant and related compensation expense is recognized ratably over the vesting period. Each restricted stock unit entitles the holder to receive one share of our common stock upon vesting. We issue new shares of our common stock upon the vesting of restricted stock units. Awards under our share tracking awards plans require cash settlement upon exercise and are classified as a liability. Accordingly, the fair value of related cash-settled awards is re-measured at each reporting date until awards are exercised or are otherwise no longer outstanding. Related changes in the fair value of outstanding cash-settled awards at each financial reporting date are recognized as adjustments to share-based compensation expense. We measure the fair value of stock to be purchased through our employee stock purchase plan at the beginning of an offering period, or grant date, and recognize related compensation expense ratably over the requisite service period (the offering period). We issue new shares of our common stock upon the end of each offering period, or exercise date.
Income Taxes	Income Taxes We account for income taxes in accordance with the asset and liability method. Under this method, we determine deferred tax assets and liabilities based on the difference between the financial statement carrying amounts and the tax bases of assets and liabilities, using enacted tax rates in effect for years in which the temporary differences are expected to reverse. We apply a valuation allowance against any net deferred tax asset if, based on the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. 2. Summary of Significant Accounting Policies (Continued) We recognize the benefit of an uncertain tax position that has been taken or that we expect to take on income tax returns only if such tax position is more likely than not to be sustained. We recognize the benefit in an amount equal to the largest amount that we determine has a greater than 50 percent likelihood of being realized upon settlement. The ultimate resolution of uncertain tax positions could result in amounts different from those recognized in our consolidated financial statements.
Earnings per Share	Earnings per Share Basic (loss) earnings per share is computed by dividing net (loss) income by the weighted average number of shares of common stock outstanding during the period. Diluted (loss) earnings per common share is computed by dividing net (loss) income by the weighted average number of shares of common stock outstanding during the period, plus the potential dilutive effect of other securities if such securities were converted or exercised. During periods in which we incur net losses, both basic and diluted loss per share are calculated by dividing the net loss by the weighted average shares outstanding. Potentially dilutive securities are excluded from the calculation because their effect would be anti-dilutive.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that are exposed to credit risk consist of cash, money market funds, certificates of deposit, marketable debt securities, and trade receivables. We maintain our cash and money market funds with financial institutions that are federally insured. While balances deposited in these institutions often exceed Federal Deposit Insurance Corporation limits, we have not experienced any losses on related accounts to date. Furthermore, we limit our risk exposure by maintaining funds in financial institutions that we believe are creditworthy and financially sound. Our investments in marketable debt securities have been issued by corporate entities and government-sponsored enterprises with high credit ratings. We mitigate investment risks by investing in highly-rated securities with relatively short maturities that we believe do not subject us to undue investment or credit risk. In addition, our investment policy does not provide for investments in complex or structured financial instruments. At any given time, our trade receivables are concentrated among a small number of principal customers. If any of these financial institutions, issuers or customers fail to perform their obligations under the terms of these financial instruments, our maximum exposure to potential losses would be equal to amounts reported on our consolidated balance sheets.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
Summary of Significant Accounting Policies (Tables)	Dec. 31, 2019
Summary of Significant Accounting Policies
Schedule of inventories, net of reserves	Inventories are stated at the lower of cost (first-in, first-out method) or net realizable value and consist of the following, net of reserves (in millions): As of December 31, 2019 2018 Raw materials $ 21.1 $ 24.3 Work-in-progress 29.1 28.0 Finished goods 43.2 48.7 Total inventories $ 93.4 $ 101.0
Schedule of goodwill and other intangible assets	Goodwill and other intangible assets comprise the following (in millions): As of December 31, 2019 As of December 31, 2018 Accumulated Accumulated Gross Amortization Net Gross Amortization Net Goodwill $ 28.0 $ — $ 28.0 $ 31.5 $ — $ 31.5 Other intangible assets: Technology, patents and trade names 6.7 (5.3) 1.4 6.7 (5.1) 1.6 In-process research and development (1) 128.9 — 128.9 137.7 — 137.7 Total $ 163.6 $ (5.3) $ 158.3 $ 175.9 $ (5.1) $ 170.8 (1) In 2018, we determined the fair value of an IPR&D asset resulting from our acquisition of SteadyMed Ltd. using the multi-period earnings method under the income approach. This method reflects the present value of the projected cash flows that are expected to be generated by the IPR&D, less charges representing the required return on other assets to sustain those cash flows.
Schedule of property, plant and equipment and the estimated useful lives	Land improvements 15 Years Buildings 25-39 Years Building improvements 10-39 Years Furniture, equipment and vehicles 3-25 Years Leasehold improvements Remaining lease term, or the estimated useful life of the improvement, whichever is shorter Property, plant and equipment consists of the following (in millions): As of December 31, 2019 2018 Land and land improvements $ 74.4 $ 69.0 Buildings, building improvements and leasehold improvements 573.3 533.3 Buildings under construction 42.0 126.5 Furniture, equipment and vehicles 318.2 205.5 1,007.9 934.3 Less—accumulated depreciation (269.4) (234.6) Property, plant and equipment, net $ 738.5 $ 699.7

Recently Issued Accounting St_2

Recently Issued Accounting Standards (Tables)	12 Months Ended
Recently Issued Accounting Standards (Tables)	Dec. 31, 2019
Recently Issued Accounting Standards
Schedule of Supplemental balance sheet information related to operating leases	Supplemental balance sheet information related to operating leases was as follows (in millions): Financial Statement Line Item on our December 31, January 1, Operating Leases Consolidated Balance Sheets 2019 2019 Right-of-use assets Other non-current assets $ 4.8 $ 8.2 Current lease liabilities Other current liabilities $ 1.8 $ 4.1 Non-current lease liabilities Other non-current liabilities 3.0 4.1 Total operating lease liabilities $ 4.8 $ 8.2

Investments (Tables)

Investments (Tables) - Available-for-Sale Debt Securities	12 Months Ended
Investments (Tables) - Available-for-Sale Debt Securities	Dec. 31, 2019
Investments
Schedule of available-for-sale debt securities	Available-for-Sale Debt Securities Available-for-sale debt securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive loss in stockholders’ equity, until realized. Available-for-sale debt securities consisted of the following (in millions): Gross Gross Amortized Unrealized Unrealized Fair As of December 31, 2019 Cost Gains Losses Value U.S. government and agency securities $ 1,225.2 $ 2.9 $ (0.2) $ 1,227.9 Corporate debt securities 222.4 1.7 — 224.1 Total $ 1,447.6 $ 4.6 $ (0.2) $ 1,452.0 Reported under the following captions on our consolidated balance sheets: Current marketable investments 684.5 Non-current marketable investments 767.5 Total $ 1,452.0 Gross Gross Amortized Unrealized Unrealized Fair As of December 31, 2018 Cost Gains Losses Value U.S. government and agency securities $ 1,077.4 $ 0.7 $ (3.9) $ 1,074.2 Corporate debt securities 72.3 — (0.3) 72.0 Total $ 1,149.7 $ 0.7 $ (4.2) $ 1,146.2 Reported under the following captions on our consolidated balance sheets: Current marketable investments 705.8 Non-current marketable investments 440.4 Total $ 1,146.2
Summary of the contractual maturities	The following table summarizes the contractual maturities of available-for-sale marketable investments (in millions): As of December 31, 2019 Amortized Fair Cost Value Due within one year $ 683.3 $ 684.5 Due in one to three years 764.3 767.5 Total $ 1,447.6 $ 1,452.0

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
Fair Value Measurements (Tables)	Dec. 31, 2019
Fair Value Measurements
Schedule of assets and liabilities subject to fair value measurements	Assets and liabilities subject to fair value measurements are as follows (in millions): As of December 31, 2019 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 270.0 $ — $ — $ 270.0 Time deposits (2) — 87.3 — 87.3 U.S. government and agency securities (3) — 1,227.9 — 1,227.9 Corporate debt securities (3) — 224.1 — 224.1 Equity securities (4) 63.0 — — 63.0 Total assets $ 333.0 $ 1,539.3 $ — $ 1,872.3 Liabilities Contingent consideration (5) — — 13.4 13.4 Total liabilities $ — $ — $ 13.4 $ 13.4 As of December 31, 2018 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 247.6 $ — $ — $ 247.6 Time deposits (2) — 35.9 — 35.9 U.S. government and agency securities (3) — 1,074.2 — 1,074.2 Corporate debt securities (3) — 75.7 — 75.7 Equity securities (4) 3.5 — — 3.5 Total assets $ 251.1 $ 1,185.8 $ — $ 1,436.9 Liabilities Contingent consideration (5) — — 13.4 13.4 Total liabilities $ — $ — $ 13.4 $ 13.4 (1) Included in cash and cash equivalents on our consolidated balance sheets. (2) Included in cash and cash equivalents and current marketable investments on our consolidated balance sheets. The fair value of these securities is principally measured or corroborated by trade data for identical securities in which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (3) Included in cash and cash equivalents and current and non-current marketable investments on our consolidated balance sheets. Refer to Note 4— Investments—Marketable Investments—Available-for-Sale Debt Securities for further information. The fair value of these securities is principally measured or corroborated by trade data for identical securities for which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (4) Included in current marketable investments on our consolidated balance sheets. The fair value of these securities is based on quoted market prices for identical instruments in active markets. During the year ended December 31, 2019, we recognized $21.4 million of net unrealized and realized gains on these securities and recorded these gains on our consolidated statements of operations within other income (expense), net. Refer to Note 4 —Investments — Marketable Investments—Investments in Equity Securities with Readily Determinable Fair Values . 5. Fair Value Measurements (Continued) (5) Included in non-current liabilities on our consolidated balance sheets. The fair value of contingent consideration has been estimated using probability-weighted discounted cash flow models (DCFs). The DCFs incorporate Level 3 inputs including estimated discount rates that we believe market participants would consider relevant in pricing and the projected timing and amount of cash flows, which are estimated and developed, in part, based on the requirements specific to each acquisition agreement. The change in the fair value of contingent consideration for the year ended December 31, 2019 was not material.

Accounts Payable and Accrued _2

Accounts Payable and Accrued Expenses (Tables)	12 Months Ended
Accounts Payable and Accrued Expenses (Tables)	Dec. 31, 2019
Accounts Payable and Accrued Expenses
Schedule of accounts payable and accrued expenses	Accounts payable and accrued expenses consist of the following by major categories (in millions): As of December 31, 2019 2018 Accounts payable $ 9.9 $ 23.1 Accrued expenses: Sales related (royalties, rebates and fees) 71.5 81.0 Payroll related 43.4 37.9 Other 23.6 24.1 Total accrued expenses $ 138.5 $ 143.0 Total accounts payable and accrued expenses $ 148.4 $ 166.1

Debt (Tables)

Debt (Tables)	12 Months Ended
Debt (Tables)	Dec. 31, 2019
Debt
Schedule of components of interest expense presented on the entity's consolidated statements of operations	Details of interest expense presented on our consolidated statements of operations are as follows (in millions): Year Ended December 31, 2019 2018 2017 Credit Facility interest expense (1) $ 44.2 $ 13.9 $ 7.1 Other interest expense — — 1.9 Total interest expense $ 44.2 $ 13.9 $ 9.0 (1) Represents interest expense related to debt and amortization of issuance costs associated with our 2018 and 2016 Credit Agreements.

Temporary Equity (Tables)

Temporary Equity (Tables)	12 Months Ended
Temporary Equity (Tables)	Dec. 31, 2019
Temporary Equity
Schedule of components of carrying value of temporary equity	Components comprising the carrying value of temporary equity include the following (in millions): As of December 31, 2019 2018 Common stock subject to repurchase (1) $ — $ 10.8 Preferred stock with redemption rights (2) — 8.4 Total $ — $ 19.2 (1) Pursuant to a license agreement with Toray Industries Inc. (Toray), we issued 200,000 shares of our common stock (which later split into 400,000 shares) to Toray in 2007, and provided Toray the right to require us to repurchase the shares at a price of $27.21 per share (the Put Right), which resulted in classification of such shares within temporary equity. During the second quarter of 2019, we terminated our license agreement with Toray and the Put Right no longer exists. As a result, upon the termination of the license agreement, we reclassified $10.8 million from temporary equity to additional paid-in capital during the second quarter of 2019. (2) The preferred stock issued by the variable interest entity we previously consolidated includes rights that allow the holders to redeem the preferred stock at the original issuance price in exchange for cash. In the third quarter of 2019, we deconsolidated the entity’s balance sheet, which included $8.4 million of temporary equity. Refer to Note 4 —Investments—Deconsolidation of a Variable Interest Entity for more information.

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
Share-Based Compensation (Tables)	Dec. 31, 2019
Stock Options
Share-Based Compensation
Schedule of components of share-based compensation expense (benefit) recognized	The following table reflects the components of share-based compensation expense (benefit) recognized in our consolidated statements of operations (in millions): Year Ended December 31, 2019 2018 2017 Stock options $ 70.5 $ 58.5 $ 43.0 Restricted stock units 13.3 7.3 2.2 STAP awards (39.7) (93.4) 27.1 Employee stock purchase plan 1.3 1.2 1.2 Total share-based compensation expense (benefit) before tax $ 45.4 $ (26.4) $ 73.5 Share-based compensation capitalized as part of inventory $ 0.7 $ 0.7 $ 0.4
Summary of weighted-average assumptions to measure the fair value of stock options	Year Ended December 31, 2019 2018 2017 Expected term of awards (in years) 5.8 6.3 6.1 Expected volatility 33.8 % 36.2 % 35.7 % Risk-free interest rate 2.4 % 2.7 % 2.2 % Expected dividend yield 0.0 % 0.0 % 0.0 %
Schedule of activity and status of stock options	Weighted Average Weighted Remaining Aggregate Average Contractual Intrinsic Exercise Term Value Options Price (in Years) (in millions) Outstanding at January 1, 2019 6,299,803 $ 120.78 Granted 2,081,047 124.87 Exercised (191,508) 51.53 Forfeited (100,662) 131.11 Outstanding at December 31, 2019 8,088,680 $ 123.34 6.3 $ 12.7 Exercisable at December 31, 2019 3,928,404 $ 119.45 5.1 $ 11.9 Unvested at December 31, 2019 4,160,276 $ 127.02 7.4 $ 0.8
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense related to stock options is recorded as follows (in millions): Year Ended December 31, 2019 2018 2017 Cost of product sales $ 0.8 $ 0.9 $ 1.3 Research and development 3.7 3.7 3.7 Selling, general and administrative 66.0 53.9 38.0 Share-based compensation expense before tax 70.5 58.5 43.0 Related income tax benefit (16.0) (13.3) (15.8) Share-based compensation expense, net of tax $ 54.5 $ 45.2 $ 27.2
Summary of stock option exercise data	Stock option exercise data is summarized below (dollars in millions): Year Ended December 31, 2019 2018 2017 Number of options exercised 191,508 289,393 461,465 Cash received from options exercised $ 9.9 $ 15.6 $ 39.9 Total intrinsic value of options exercised $ 11.5 $ 17.0 $ 29.3 Tax benefits realized from options exercised (1) $ 2.6 $ 3.9 $ 10.6 (1) We recognize these tax benefits on our consolidated statements of operations within income tax benefit (expense).
Restricted Stock Units
Share-Based Compensation
Schedule of restricted stock units activity	Weighted Average Weighted Remaining Aggregate Number of Average Contractual Intrinsic Restricted Grant Term Value Stock Units Price (in Years) (in millions) Unvested at January 1, 2019 186,255 $ 112.48 Granted 225,218 112.69 Vested (74,324) 111.94 Forfeited/canceled (26,424) 118.62 Unvested at December 31, 2019 310,725 $ 112.24 8.9 $ 27.4
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense relating to restricted stock units is recorded as follows (in millions): Year Ended December 31, 2019 2018 2017 Cost of product sales $ 1.0 $ 0.5 $ — Research and development 4.4 1.7 — Selling, general and administrative 7.9 5.1 2.2 Share-based compensation expense before tax 13.3 7.3 2.2 Related income tax benefit (3.0) (1.7) (0.8) Share-based compensation expense, net of tax $ 10.3 $ 5.6 $ 1.4
STAP awards
Share-Based Compensation
Summary of weighted-average assumptions to measure the fair value of stock options	As of December 31, 2019 2018 2017 Expected term of awards (in years) 2.0 2.5 1.8 Expected volatility 29.1 % 30.9 % 31.7 % Risk-free interest rate 1.6 % 2.5 % 1.8 % Expected dividend yield 0.0 % 0.0 % 0.0 %
Schedule of share-based compensation expense (benefit) recognized	Share-based compensation (benefit) expense recognized in connection with STAP awards is as follows (in millions): Year Ended December 31, 2019 2018 2017 Cost of product sales $ (1.7) $ (4.7) $ 1.2 Research and development (8.2) (17.9) 4.1 Selling, general and administrative (29.8) (70.8) 21.8 Share-based compensation (benefit) expense before tax (39.7) (93.4) 27.1 Related income tax expense (benefit) 9.0 21.3 (10.0) Share-based compensation (benefit) expense, net of tax $ (30.7) $ (72.1) $ 17.1
Summary of the activity and status of STAP awards	A summary of the activity and status of STAP awards during the year ended December 31, 2019 is presented below: Weighted Average Weighted- Remaining Aggregate Average Contractual Intrinsic Number of Exercise Term Value Awards Price (Years) (in millions) Outstanding at January 1, 2019 2,867,979 $ 107.85 Granted — — Exercised (156,876) 59.05 Forfeited (88,775) 157.26 Outstanding at December 31, 2019 2,622,328 $ 109.10 4.1 $ 29.9 Exercisable at December 31, 2019 2,612,328 $ 109.32 4.1 $ 29.5 Unvested at December 31, 2019 10,000 $ 52.57 2.9 $ 0.4

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
Stockholders' Equity (Tables)	Dec. 31, 2019
Stockholders' Equity
Schedule of components of basic and diluted earnings (loss) per common share	Year Ended December 31, 2019 2018 2017 Numerator: Net (loss) income $ (104.5) $ 589.2 $ 417.9 Denominator: Weighted average outstanding shares—basic 43.8 43.5 44.0 Effect of dilutive securities (1) : Warrants — — 0.1 Stock options, restricted stock units and employee stock purchase plan — 0.5 0.8 Weighted average shares—diluted (2) 43.8 44.0 44.9 Net (loss) income per common share: Basic $ (2.39) $ 13.54 $ 9.50 Diluted $ (2.39) $ 13.39 $ 9.31 Stock options, restricted stock units, shares issuable under the ESPP and warrants excluded from calculation (2) 7.2 4.7 3.3 (1) Calculated using the treasury stock method. (2) Certain stock options, restricted stock units, shares issuable under the ESPP and warrants have been excluded from the computation of diluted (loss) earnings per share because their impact would be anti-dilutive.
Schedule of changes in accumulated other comprehensive loss by component, net of tax	The following table includes changes in accumulated other comprehensive loss by component, net of tax (in millions): Unrealized Gains and Defined Foreign (Losses) on Benefit Currency Available-for- Pension Translation Sale Plan (1) Losses Securities Total Balance, January 1, 2019 $ 12.3 $ (17.9) $ (2.3) $ (7.9) Other comprehensive (loss) income before reclassifications (10.6) — 6.0 (4.6) Amounts reclassified from accumulated other comprehensive loss (1.7) — — (1.7) Net current-period other comprehensive (loss) income (12.3) — 6.0 (6.3) Balance, December 31, 2019 $ — $ (17.9) $ 3.7 $ (14.2) Unrealized Gains and Defined Foreign (Losses) on Benefit Currency Available-for- Pension Translation Sale Plan (1) Losses Securities Total Balance, January 1, 2018 $ 0.2 $ (17.9) $ (1.9) $ (19.6) Other comprehensive income (loss) before reclassifications 10.7 — (0.4) 10.3 Amounts reclassified from accumulated other comprehensive loss 1.4 — — 1.4 Net current-period other comprehensive income (loss) 12.1 — (0.4) 11.7 Balance, December 31, 2018 $ 12.3 $ (17.9) $ (2.3) $ (7.9) (1) Refer to Note 12— Employee Benefit Plans — Supplemental Executive Retirement Plan , which identifies the captions within our consolidated statements of operations where reclassification adjustments were recognized and their associated tax impact.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2019
Income Taxes
Schedule of components of income tax (benefit) expense	Components of income tax (benefit) expense consist of the following (in millions): Year Ended December 31, 2019 2018 2017 Current: Federal $ 63.1 $ 136.6 $ 261.3 State 9.4 17.4 23.9 Total current 72.5 154.0 285.2 Deferred Federal (120.1) 12.7 67.2 State (12.9) 3.0 (0.8) Total deferred (133.0) 15.7 66.4 Total income tax (benefit) expense $ (60.5) $ 169.7 $ 351.6
Schedule of reconciliation of income tax expense computed at the statutory federal tax rate to income tax expense	Presented below is a reconciliation of income tax (benefit) expense computed at the statutory federal tax rate of 21 percent in 2019 and 2018, and 35 percent in 2017 to income tax (benefit) expense as reported (in millions): Year Ended December 31, 2019 2018 2017 Federal taxes at the statutory rate $ (34.7) $ 159.4 $ 269.2 General business credits (20.4) (14.9) (15.1) Nondeductible compensation expense 6.3 2.1 1.8 Change in valuation allowance (5.7) 11.2 17.5 Foreign income adjustment 5.1 — — State taxes, net of federal benefit (4.0) 15.3 14.2 Deduction for foreign-derived intangible income (3.3) (3.3) — Deconsolidation of VIE (1.9) — — Other (1.6) 3.6 1.3 Excess tax benefits from share-based compensation (0.3) (1.9) (4.5) Tax reform — (1.8) 71.0 Section 199 deduction — — (22.8) Nondeductible portion of DOJ Settlement — — 19.0 Total income tax (benefit) expense $ (60.5) $ 169.7 $ 351.6
Schedule of components of net deferred tax assets	Components of the net deferred tax assets are as follows (in millions): As of December 31, 2019 2018 Deferred tax assets: Intangible assets $ 192.4 $ 36.5 Share-based compensation 56.0 57.0 Impairments 25.8 23.1 SERP 10.1 10.7 NOLs 6.7 34.3 Reserves 6.5 9.3 Other 14.6 20.7 Total deferred tax assets 312.1 191.6 Deferred tax liabilities: Plant and equipment principally due to differences in depreciation (40.7) (20.2) Basis differences in foreign entities 0.6 (24.8) Other (5.4) (8.3) Net deferred tax assets before valuation allowance 266.6 138.3 Valuation allowance (36.6) (42.6) Net deferred tax assets $ 230.0 $ 95.7

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
Employee Benefit Plans (Tables)	Dec. 31, 2019
Employee Benefit Plans
Schedule of reconciliation of the beginning and ending balances of the projected benefit obligation	A reconciliation of the beginning and ending balances of the projected benefit obligation is presented below (in millions): Year Ended December 31, 2019 2018 Projected benefit obligation at the beginning of the year $ 46.8 $ 55.9 Service cost 2.2 2.4 Interest cost 1.4 1.6 Benefits paid (5.1) (0.2) Net actuarial loss (gain) (1) 10.8 (12.9) Projected benefit obligation at the end of the year $ 56.1 $ 46.8 Amount included in Other current liabilities (2) $ 17.5 $ 19.9 Amount included in Other non-current liabilities $ 38.6 $ 26.9 (1) During the fourth quarter of 2018, a participant in the SERP departed before retirement age under the terms of the SERP. As a result, we recorded a $7.0 million reduction to the benefit obligation as of December 31, 2018. (2) This amount represents the benefit obligation due to participants who are eligible to retire and whose benefit payments could commence within one year of the respective balance sheet date.
Schedule of weighted-average assumptions used to measure the SERP obligation	Year Ended December 31, 2019 2018 Discount rate 2.63 % 3.92 % Salary increases 4.00 % 4.00 % Lump-sum distribution rate 3.00 % 4.50 %
Schedule of components of net periodic pension cost recognized	The components of net periodic pension cost recognized on our consolidated statements of operations consisted of the following (in millions): Year Ended December 31, 2019 2018 2017 Service cost $ 2.2 $ 2.4 $ 2.2 Interest cost 1.4 1.6 1.6 Amortization of prior service cost 1.5 1.5 1.5 Amortization of net actuarial gain (2.2) (0.2) (0.6) Settlement (1.9) — — Total $ 1.0 $ 5.3 $ 4.7
Schedule of amounts recognized in other comprehensive (loss) income	Amounts related to the SERP that have been recognized in other comprehensive (loss) income are as follows (in millions): Year Ended December 31, 2019 2018 2017 Net actuarial (loss) gain $ (12.9) $ 12.7 $ (3.2) Prior service cost 1.5 1.5 1.5 Settlement (1.9) — — Total recognized in other comprehensive (loss) income (13.3) 14.2 (1.7) Tax benefit (expense) 1.0 (2.1) 0.6 Total, net of tax $ (12.3) $ 12.1 $ (1.1)
Schedule of amounts included in accumulated other comprehensive loss that have not yet been recognized as a component of net periodic pension cost	The table below presents amounts related to the SERP included in accumulated other comprehensive loss that have not yet been recognized as a component of net periodic pension cost on our consolidated statements of operations (in millions): Year Ended December 31, 2019 2018 2017 Net actuarial gain $ (4.5) $ (19.3) $ (6.6) Prior service cost 3.3 4.7 6.2 Total included in accumulated other comprehensive loss (1.2) (14.6) (0.4) Tax expense 1.2 2.3 0.2 Total, net of tax $ — $ (12.3) $ (0.2)
Schedule of future estimated benefit payments, based on current assumptions, including election of lump-sum distributions and expected future service	Future estimated benefit payments, based on current assumptions, including election of lump-sum distributions and expected future service, are as follows (in millions): Year Ended December 31, 2020 $ 17.5 2021 — 2022 — 2023 6.2 2024 16.1 Thereafter 44.8 Total $ 84.6

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
Commitments and Contingencies (Tables)	Dec. 31, 2019
Commitments and Contingencies
Schedule of future minimum lease payments under non-cancelable operating leases	Future minimum lease payments under non-cancelable operating leases as of December 31, 2019, are as follows (in millions): Year Ending December 31, 2020 $ 2.1 2021 1.7 2022 1.0 2023 0.7 2024 0.4 Thereafter 0.6 Total $ 6.5
Schedule of financial obligation under various agreements	Counterparty Relevant Product Our Financial Obligation Supernus Pharmaceuticals, Inc. Orenitram Single-digit Lilly Adcirca Five percent royalty on net product sales of Adcirca through November 2017; from December 1, 2017 through December 31, 2020, ten percent royalty on net sales, plus milestone payments of $325,000 for each $1,000,000 in net product sales The Scripps Research Institute Unituxin One percent royalty on net product sales of Unituxin Medtronic, Inc. Implantable System for Remodulin Ten percent royalty on net product sales of Remodulin delivered via the Implantable System for Remodulin. Reimbursement of Medtronic’s development costs and costs incurred in providing commercialization support DEKA Research & Development Corp. Remunity Product fees and single-digit Samumed LLC LNG01 (formerly SM04646) Low double-digit royalties on LNG01 net product sales and up to $340.0 million in developmental milestone payments 13. Commitments and Contingencies (Continued) Counterparty Relevant Product Our Financial Obligation MannKind Corporation Treprostinil Technosphere Low double-digit royalties on net product sales of Treprostinil Technosphere and up to $50.0 million in developmental milestone payments (of which $25.0 million have already been paid) Arena Ralinepag Low double-digit, tiered royalties on net product sales of ralinepag (any route of administration); a one-time payment of $250.0 million upon FDA approval of an inhaled formulation of ralinepag to treat PAH; and a one-time payment of $150.0 million upon approval in certain non-US jurisdictions of an oral version of ralinepag to treat any indication

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
Segment Information (Tables)	Dec. 31, 2019
Segment Information
Schedule of net product sales, cost of product sales and gross profit for each commercial product	Net product sales, cost of product sales and gross profit for each of our commercial products were as follows (in millions): Remodulin Tyvaso Orenitram Unituxin Adcirca Total Year Ended December 31, 2019 Net product sales $ 587.0 $ 415.6 $ 225.3 $ 113.7 $ 107.2 $ 1,448.8 Cost of product sales 21.1 19.6 15.0 15.7 46.2 117.6 Gross profit $ 565.9 $ 396.0 $ 210.3 $ 98.0 $ 61.0 $ 1,331.2 Year Ended December 31, 2018 Net product sales $ 599.0 $ 415.2 $ 205.1 $ 84.8 $ 323.7 $ 1,627.8 Cost of product sales 14.1 17.3 13.2 14.3 139.8 198.7 Gross profit $ 584.9 $ 397.9 $ 191.9 $ 70.5 $ 183.9 $ 1,429.1 Year Ended December 31, 2017 Net product sales $ 670.9 $ 372.9 $ 185.8 $ 76.0 $ 419.7 $ 1,725.3 Cost of product sales 15.9 18.5 15.3 12.9 43.1 105.7 Gross profit $ 655.0 $ 354.4 $ 170.5 $ 63.1 $ 376.6 $ 1,619.6
Schedule of net revenues from external customers by geographic area	Geographic revenues are determined based on the country in which our customers (distributors) are located. Total revenues from external customers by geographic area are as follows (in millions): Year Ended December 31, 2019 2018 2017 United States $ 1,323.2 $ 1,528.2 $ 1,536.8 Rest-of-World (1) 125.6 99.6 188.5 Total $ 1,448.8 $ 1,627.8 $ 1,725.3 (1) Primarily Europe.
Schedule of concentration risk disclosure	We recorded revenue from two distributors in the United States that exceeded 10 percent of total revenues. Revenue from these two distributors as a percentage of total revenues is as follows: Year Ended December 31, 2019 2018 2017 Distributor 1 54 % 51 % 46 % Distributor 2 22 % 18 % 15 %
Schedule of long-lived assets (property, plant and equipment) located by geographic area	Long-lived assets (property, plant and equipment) located by geographic area are as follows (in millions): Year Ended December 31, 2019 2018 2017 United States $ 723.1 $ 684.0 $ 544.5 Rest-of-World 15.4 15.7 1.2 Total $ 738.5 $ 699.7 $ 545.7

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
Quarterly Financial Information (Unaudited) (Tables)	Dec. 31, 2019
Quarterly Financial Information (Unaudited)
Summary of quarterly financial information	Summarized quarterly financial information for each of the years ended December 31, 2019 and 2018 are as follows (in millions, except per share amounts): Quarter Ended December 31, September 30, June 30, March 31, 2019 2019 2019 2019 Total revenues $ 311.1 $ 401.5 $ 373.6 $ 362.6 Cost of product sales 28.8 33.0 26.7 29.1 Gross profit 282.3 368.5 346.9 333.5 Net income (loss) (1) 52.6 132.4 205.1 (494.6) Net income (loss) per share—basic $ 1.20 $ 3.02 $ 4.68 $ (11.32) Net income (loss) per share—diluted $ 1.20 $ 3.01 $ 4.66 $ (11.32) 15. Quarterly Financial Information (Unaudited) (Continued) Quarter Ended December 31, September 30, June 30, March 31, 2018 2018 2018 2018 Total revenues $ 381.4 $ 412.7 $ 444.5 $ 389.2 Cost of product sales 31.9 51.9 61.7 53.2 Gross profit 349.5 360.8 382.8 336.0 Net income (2) 65.3 106.5 172.9 244.5 Net income per share—basic $ 1.50 $ 2.44 $ 4.01 $ 5.65 Net income per share—diluted $ 1.48 $ 2.42 $ 3.98 $ 5.57 (1) Operating results for the quarters ended December 31, 2019, September 30, 2019, June 30, 2019 and March 31, 2019 included $5.6 million, $1.2 million, $(46.0) million and $8.5 million, net of tax, for STAP related share-based compensation expense (benefit), respectively. (2) Operating results for the quarters ended December 31, 2018, September 30, 2018, June 30, 2018 and March 31, 2018 included $(10.3) million, $24.8 million, $2.1 million and $(88.7) million, net of tax, for STAP related share-based compensation (benefit) expense, respectively.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Inventories
Raw materials	$ 21.1	$ 24.3
Work-in-progress	29.1	28
Finished goods	43.2	48.7
Total inventories	$ 93.4	$ 101

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Other Intangible Assets
Goodwill wrote off	$ 3.5		$ 3.5
Impairment loss for goodwill				$ 0
Impairment losses of indefinite-lived intangible assets			0	0
Goodwill, Gross			28	31.5
Goodwill, Net			28	31.5
Total goodwill and other intangible assets, Gross			163.6	175.9
Other intangible assets, Accumulated Amortization			(5.3)	(5.1)
Total goodwill and other intangible assets, Net			158.3	170.8
Amortization expense			0.2	0.1	$ 0.5
Maximum
Amortization relating to other intangible assets
2020			0
2021			0
2022			0
2023			0
2024			0
Thereafter			1
Technology, patents and trade names
Goodwill and Other Intangible Assets
Other intangible assets, Gross			6.7	6.7
Other intangible assets, Accumulated Amortization			(5.3)	(5.1)
Other intangible assets, Net			1.4	1.6
In-process research and development
Goodwill and Other Intangible Assets
Impairment charges		$ 8.8	8.8
Other intangible assets, Gross			128.9	137.7
Other intangible assets, Net			$ 128.9	$ 137.7

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment
Property, plant and equipment, gross	$ 1,007.9	$ 934.3
Less-accumulated depreciation	(269.4)	(234.6)
Property, plant and equipment, net	738.5	699.7	$ 545.7
Depreciation expense	45.7	35.8	$ 30.5
Reclassification from Property, Plant and Equipment to Other Noncurrent Assets	$ 23.7
Land improvements
Property, Plant and Equipment
Estimated useful life	15 years
Land and land improvements
Property, Plant and Equipment
Property, plant and equipment, gross	$ 74.4	69
Buildings, building improvements and leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, gross	$ 573.3	533.3
Buildings \| Minimum
Property, Plant and Equipment
Estimated useful life	25 years
Buildings \| Maximum
Property, Plant and Equipment
Estimated useful life	39 years
Building improvements \| Minimum
Property, Plant and Equipment
Estimated useful life	10 years
Building improvements \| Maximum
Property, Plant and Equipment
Estimated useful life	39 years
Buildings under construction
Property, Plant and Equipment
Property, plant and equipment, gross	$ 42	126.5
Furniture, equipment and vehicles
Property, Plant and Equipment
Property, plant and equipment, gross	$ 318.2	$ 205.5
Furniture, equipment and vehicles \| Minimum
Property, Plant and Equipment
Estimated useful life	3 years
Furniture, equipment and vehicles \| Maximum
Property, Plant and Equipment
Estimated useful life	25 years

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Revenue Recognition (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)product	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Number of disclosed commercially approved products \| product	5
Decrease in net product sales	$ 2.3
Increase in net product sales		$ 8.8
Rebate liability reversal		13.6
Maximum payment period for rebates and chargebacks	6 months
Accrued rebates and chargebacks	$ 51.7	54.7
Revenue deductions, rebates and chargebacks	$ 178.7	223.7	$ 241.5
Maximum payment period for prompt pay discounts to distributors	30 days
Expiration period for right to return product	12 months
Allowance for product returns	$ (6.2)	17.5	$ 0.9
Adcirca
Allowance for product returns	$ 14.2	$ 22.4
Minimum
Expiration period of products from the initial sale date	24 months
Period of accounts receivable from customers	30 days
Minimum \| Unituxin
Expiration period of products from the initial sale date	9 months
Maximum
Expiration period of products from the initial sale date	36 months
Period of accounts receivable from customers	90 days
Maximum \| Unituxin
Expiration period of products from the initial sale date	14 months

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Share-Based Compensation (Details)	Dec. 31, 2019item
Restricted Stock Units
Share-Based Compensation
Number of shares of common stock entitled for each unit upon vesting	1

Recently Issued Accounting St_3

Recently Issued Accounting Standards (Details) - USD ($) $ in Millions	Jan. 01, 2019	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2017
Leases
Decrease to retained earnings			$ (5.1)	$ (5.1)
Right-of-use assets	$ 8.2		$ 4.8
Other non-current assets	us-gaap:OtherAssetsNoncurrent		us-gaap:OtherAssetsNoncurrent
Current lease liabilities	$ 4.1		$ 1.8
Other current liabilities	us-gaap:OtherLiabilitiesCurrent		us-gaap:OtherLiabilitiesCurrent
Non-current lease liabilities	$ 4.1		$ 3
Other non-current liabilities	us-gaap:OtherLiabilitiesNoncurrent		us-gaap:OtherLiabilitiesNoncurrent
Total operating lease liabilities	$ 8.2		$ 4.8
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OperatingLeaseLiabilityCurrent us-gaap:OperatingLeaseLiabilityNoncurrent		us-gaap:OperatingLeaseLiabilityCurrent us-gaap:OperatingLeaseLiabilityNoncurrent
Reclassification from Property, plant and equipment to other noncurrent assets			$ 23.7
Broader collaboration arrangement
Leases
Reclassification from Property, plant and equipment to other noncurrent assets		$ 23.7
ASU 2016-02
Leases
Decrease to retained earnings	$ (5.1)
Weighted-average remaining lease term	3 years
Weighted-average discount rate	4.90%

Investments - Available-for-Sal

Investments - Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	$ 1,447.6	$ 1,149.7
Gross Unrealized Gains	4.6	0.7
Gross Unrealized Losses	(0.2)	(4.2)
Fair Value	1,452	1,146.2
U.S. government and agency securities
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	1,225.2	1,077.4
Gross Unrealized Gains	2.9	0.7
Gross Unrealized Losses	(0.2)	(3.9)
Fair Value	1,227.9	1,074.2
Corporate debt securities
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	222.4	72.3
Gross Unrealized Gains	1.7
Gross Unrealized Losses		(0.3)
Fair Value	$ 224.1	$ 72

Investments - Current and Non-c

Investments - Current and Non-current of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Reported under the following captions on our consolidated balance sheet:
Total	$ 1,452	$ 1,146.2
Current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	684.5	705.8
Non-current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	$ 767.5	$ 440.4

Investments - Contractual Matur

Investments - Contractual Maturities of Available-for-Sale Marketable Investments (Details) $ in Millions	Dec. 31, 2019USD ($)
Amortized Cost
Due within one year	$ 683.3
Due in one to three years	764.3
Total	1,447.6
Fair Value
Due within one year	684.5
Due in one to three years	767.5
Total	$ 1,452

Investments - Held-to-Maturity

Investments - Held-to-Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Investments
Marketable Investments classified as held-to-maturity	$ 0	$ 39.6

Investments - Investments in Pr

Investments - Investments in Privately-Held Companies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments in Privately-Held Companies and Investments in Equity Securities with Readily Determinable Fair Values
Payments to Acquire Long-term Investments	$ 8	$ 5	$ 60.4
Impairment of Investments in Privately Held Companies		53.5	49.6
Privately-held Companies
Investments in Privately-Held Companies and Investments in Equity Securities with Readily Determinable Fair Values
Investments in Privately-Held Companies	86
Payments to Acquire Long-term Investments	8	5
Impairment of Investments in Privately Held Companies	$ 0	$ 53.5	$ 49.6

Investments - Variable Interest

Investments - Variable Interest Entity (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Apr. 30, 2017	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity
Assets				$ 3,913.4	$ 3,401
Net loss of consolidation entity				57.6
Goodwill on deconsolidation		$ 3.5		3.5
Property, Plant and Equipment [Member] \| Variable Interest Entity
Variable Interest Entity
Assets				$ 57.6
Privately-held Companies \| Variable Interest Entity
Variable Interest Entity
Investment purchased during the period	$ 7.5
Impairment charge on research and development			$ 8.8
Goodwill on deconsolidation		3.5
Temporary Equity Derecognized		8.4
Net loss on deconsolidating		$ (2)

Investments - Investments in Eq

Investments - Investments in Equity Securities with Readily Determinable Fair Values (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Equity securities
Investments in Equity Securities with Readily Determinable Fair Values
Investments in equity securities with readily determinable fair value	$ 63	$ 3.5

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Equity securities \| Other income (expense), net
Liabilities
Net unrealized and realized gains on securities	$ 21.4
Recurring fair value measurements \| Level 1
Assets
Total assets	333	$ 251.1
Recurring fair value measurements \| Level 1 \| Money market funds
Assets
Total assets	270	247.6
Recurring fair value measurements \| Level 1 \| Equity securities
Assets
Total assets	63	3.5
Recurring fair value measurements \| Level 2
Assets
Total assets	1,539.3	1,185.8
Recurring fair value measurements \| Level 2 \| Time deposits
Assets
Total assets	87.3	35.9
Recurring fair value measurements \| Level 2 \| U.S. government and agency securities
Assets
Total assets	1,227.9	1,074.2
Recurring fair value measurements \| Level 2 \| Corporate debt securities
Assets
Total assets	224.1	75.7
Recurring fair value measurements \| Level 3
Liabilities
Contingent consideration	13.4	13.4
Total liabilities	13.4	13.4
Recurring fair value measurements \| Balance
Assets
Total assets	1,872.3	1,436.9
Liabilities
Contingent consideration	13.4	13.4
Total liabilities	13.4	13.4
Recurring fair value measurements \| Balance \| Money market funds
Assets
Total assets	270	247.6
Recurring fair value measurements \| Balance \| Time deposits
Assets
Total assets	87.3	35.9
Recurring fair value measurements \| Balance \| U.S. government and agency securities
Assets
Total assets	1,227.9	1,074.2
Recurring fair value measurements \| Balance \| Corporate debt securities
Assets
Total assets	224.1	75.7
Recurring fair value measurements \| Balance \| Equity securities
Assets
Total assets	$ 63	$ 3.5

Accounts Payable and Accrued _3

Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accounts payable
Accounts payable	$ 9.9	$ 23.1
Accrued expenses:
Sales related (royalties, rebates and fees)	71.5	81
Payroll related	43.4	37.9
Other	23.6	24.1
Total accrued expenses	138.5	143
Total accounts payable and accrued expenses	$ 148.4	$ 166.1

Debt (Details)

Debt (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jan. 24, 2019	Jun. 30, 2018	Mar. 31, 2019	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 27, 2018	Jun. 01, 2017	Jan. 31, 2016	Oct. 31, 2011
Debt
Debt issuance costs					$ 0.7	$ 13.2	$ 0.7
Upfront payment			$ 800
Line of credit (current)					250
2018 Credit Agreement
Debt
Upfront payment	$ 800
Line Of Credit Repaid During The Period					200
Outstanding Balance					250	$ 850
Debt aggregate principal value								$ 250
2018 Credit Agreement \| Other current assets
Debt
Debt issuance costs capitalized					3.4
2018 Credit Agreement \| Other non-current assets
Debt
Debt issuance costs capitalized					$ 9.3
2018 Credit Agreement \| Arena Pharmaceuticals, Inc.
Debt
Borrowing	$ 800
First unsecured revolving credit facility
Debt
Borrowing		$ 1,000
Second unsecured revolving credit facility
Debt
Borrowing		500
Increase in borrowing capacity		$ 300
2016 Credit Agreement
Debt
Borrowing										$ 1,000
Debt aggregate principal value									$ 250
Convertible Notes Due 2016
Debt
Debt aggregate principal value											$ 250
Stated percentage rate											1.00%
Sale of warrant
Share warrant, number of shares											5.2
Share warrant, strike price (in dollars per share)											$ 67.56
Shares issued upon expiration of warrants previously held as treasury stock (shares)				2.8
Shares issued upon expiration of warrants (shares)				1.7

Debt - Interest Expense (Detail

Debt - Interest Expense (Details) - USD ($) $ in Millions	12 Months Ended
Debt - Interest Expense (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest expense
Other interest expense			$ 1.9
Total interest expense	$ 44.2	$ 13.9	9
2018 and 2016 Credit Agreements
Interest expense
Interest expense	$ 44.2	$ 13.9	$ 7.1

Temporary Equity (Details)

Temporary Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Temporary Equity
Common stock subject to repurchase			$ 10.8
Preferred stock with redemption rights		$ 8.4
Temporary equity				$ 19.2
Temporary equity common stock subject to repurchase
Temporary Equity
Common stock subject to repurchase				10.8
Common stock issued (in shares)	200,000
Common stock issued split (in shares)	400,000
Repurchase price (in dollars per share)	$ 27.21
Preferred stock
Temporary Equity
Preferred stock with redemption rights				$ 8.4

Share-Based Compensation - Gene

Share-Based Compensation - General (Details)	1 Months Ended	12 Months Ended
Share-Based Compensation - General (Details)	Feb. 28, 2019shares	Dec. 31, 2019itemshares
Share-Based Compensation
Number of equity incentive plans \| item		2
2015 Plan
Share-Based Compensation
Maximum number of shares authorized to be issued		9,500,000
Additional number of shares authorized to be issued		450,000
2019 Inducement Plan \| Newly-hired employees
Share-Based Compensation
Number of equity incentive plans		1
Granted (in shares)	99,000
Amended and Restated Equity Incentive Plan (The 1999 Plan)
Share-Based Compensation
Granted (in shares)		0

Share-Based Compensation - Allo

Share-Based Compensation - Allocation of Compensation Expense (Benefit) by Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-Based Compensation
Share-based compensation expense (benefit) before tax	$ 45.4	$ (26.4)	$ 73.5
Share-based compensation capitalized as part of inventory	0.7	0.7	0.4
Cumulative effect of accounting change	(5.1)		(5.1)
Stock Options
Share-Based Compensation
Share-based compensation expense (benefit) before tax	70.5	58.5	43
Restricted Stock Units
Share-Based Compensation
Share-based compensation expense (benefit) before tax	13.3	7.3	2.2
STAP awards
Share-Based Compensation
Share-based compensation expense (benefit) before tax	(39.7)	(93.4)	27.1
Employee Stock Purchase Plan
Share-Based Compensation
Share-based compensation expense (benefit) before tax	1.3	$ 1.2	$ 1.2
ASU 2016-09
Share-Based Compensation
Cumulative effect of accounting change	$ (5.8)

Share-Based Compensation - Assu

Share-Based Compensation - Assumptions For Stock Options (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-Based Compensation
Share-based compensation expense before tax		$ 45.4	$ (26.4)	$ 73.5
Stock Options
Share-Based Compensation
Granted (in shares)		2,081,047
Total grant date fair value of employee stock options that vested		$ 37.4	33.9	13.1
Share-based compensation expense before tax		$ 70.5	$ 58.5	$ 43
Expected volatility maximum period		5 years
Method and assumptions on valuation of stock options
Expected term of awards (in years)		5 years 9 months 18 days	6 years 3 months 18 days	6 years 1 month 6 days
Expected volatility (as a percent)		33.80%	36.20%	35.70%
Risk-free interest rate (as a percent)		2.40%	2.70%	2.20%
Expected dividend yield (as a percent)		0.00%	0.00%	0.00%
Stock Options \| 2015 Plan \| Minimum
Share-Based Compensation
Share-based awards, vesting period	1 year
Stock Options \| 2015 Plan \| Maximum
Share-Based Compensation
Share-based awards, vesting period	3 years

Share-Based Compensation - Stoc

Share-Based Compensation - Stock and Status (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Options
Outstanding at beginning of year (in shares)	6,299,803
Granted (in shares)	2,081,047
Exercised (in shares)	(191,508)	(289,393)	(461,465)
Forfeited/canceled (in shares)	(100,662)
Outstanding at the end of year (in shares)	8,088,680	6,299,803
Exercisable at the end of year (in shares)	3,928,404
Unvested at the end of year (in shares)	4,160,276
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 120.78
Granted (in dollars per share)	124.87
Exercised (in dollars per share)	51.53
Forfeited (in dollars per share)	131.11
Outstanding at the end of year (in dollars per share)	123.34	$ 120.78
Exercisable at the end of year (in dollars per share)	119.45
Unvested at the end of year (in dollars per share)	$ 127.02
Weighted Average Remaining Contractual Term (in Years)
Outstanding at the end of year (in Years)	6 years 3 months 18 days
Exercisable at the end of year (in Years)	5 years 1 month 6 days
Unvested at the end of year (in Years)	7 years 4 months 24 days
Outstanding at the end of year	$ 12.7
Exercisable at the end of year	11.9
Unvested at the end of year	$ 0.8
Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value Disclosures [Abstract]
Weighted average grant date fair value of stock options (in dollars per share)	$ 39.63	$ 45.01	$ 56.07
Total grant date fair value of employee stock options that vested	$ 37.4	$ 33.9	$ 13.1

Share-Based Compensation - Shar

Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based compensation expense
Share-based compensation expense before tax	$ 45.4	$ (26.4)	$ 73.5
Stock Options
Share-based compensation expense
Share-based compensation expense before tax	70.5	58.5	43
Related income tax benefit	(16)	(13.3)	(15.8)
Share-based compensation expense, net of tax	54.5	45.2	27.2
Unrecognized compensation cost	$ 90.1
Weighted average remaining vesting period (in years)	2 years 6 months
Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	$ 13.3	7.3	2.2
Related income tax benefit	(3)	(1.7)	(0.8)
Share-based compensation expense, net of tax	10.3	5.6	1.4
Unrecognized compensation cost	$ 24.1
Weighted average remaining vesting period (in years)	1 year 10 months 24 days
Cost of product sales \| Stock Options
Share-based compensation expense
Share-based compensation expense before tax	$ 0.8	0.9	1.3
Cost of product sales \| Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	1	0.5
Research and development \| Stock Options
Share-based compensation expense
Share-based compensation expense before tax	3.7	3.7	3.7
Research and development \| Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	4.4	1.7
Selling, general and administrative \| Stock Options
Share-based compensation expense
Share-based compensation expense before tax	66	53.9	38
Selling, general and administrative \| Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	$ 7.9	$ 5.1	$ 2.2

Share-Based Compensation - St_2

Share-Based Compensation - Stock Options Exercise Data (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of stock option exercise data
Cash received from options exercised	$ 9.9	$ 15.6	$ 39.9
Stock Options
Summary of stock option exercise data
Number of options exercised (in shares)	191,508	289,393	461,465
Cash received from options exercised	$ 9.9	$ 15.6	$ 39.9
Total intrinsic value of options exercised	11.5	17	29.3
Tax benefits realized from options exercised	$ 2.6	$ 3.9	$ 10.6

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Options Activity and Status (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)item$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)
Aggregate Intrinsic Value
Share-based compensation expense before tax \| $	$ 45.4	$ (26.4)	$ 73.5
Restricted Stock Units
Share-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Entitled To Receive For Each Unit Upon Vesting \| item	1
Number of Restricted Stock Units
Unvested at beginning of year (in shares) \| shares	186,255
Granted (in shares) \| shares	225,218
Vested (in shares) \| shares	(74,324)
Forfeited/cancelled (in shares) \| shares	(26,424)
Unvested at the end of year (in shares) \| shares	310,725	186,255
Weighted-Average Grant Price
Unvested at beginning of year (in dollars per share) \| $ / shares	$ 112.48
Granted (in dollars per share) \| $ / shares	112.69
Vested (in dollars per share) \| $ / shares	111.94
Forfeited/cancelled (in dollars per share) \| $ / shares	118.62
Unvested at the end of year (in dollars per share) \| $ / shares	$ 112.24	$ 112.48
Weighted Average Remaining Contractual Term (Years)
Outstanding at the end of year (Years)	8 years 10 months 24 days
Aggregate Intrinsic Value
Unvested at the end of year (in dollars) \| $	$ 27.4
Share-based compensation expense before tax \| $	$ 13.3	$ 7.3	$ 2.2

Share-Based Compensation - STAP

Share-Based Compensation - STAP awards (Details) - STAP awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Awards granted
Grant expiration period from the grant date	4 years
Aggregate STAP liability	$ 25	$ 72.2
Expected term of awards under historic approach (in years)	1 year
Increase in share tracking award plan liability	$ 22.7
Weighted-average assumptions used to measure the fair value of the outstanding STAP awards:
Expected term of awards (in years)	2 years	2 years 6 months	1 year 9 months 18 days
Expected volatility (as a percent)	29.10%	30.90%	31.70%
Risk-free interest rate (as a percent)	1.60%	2.50%	1.80%
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%
Closing price of common stock (in dollars per share)	$ 88.08	$ 108.90	$ 147.95
Share-based awards activity
Outstanding at January 1, 2019	2,867,979
Exercised (in shares)	(156,876)
Forfeited/cancelled (in shares)	(88,775)
Outstanding at December 31, 2019	2,622,328	2,867,979
Exercisable at December 31, 2019	2,612,328
Unvested at December 31, 2019	10,000
Share awards, Weighted-Average Exercise Price
Outstanding at January 1, 2019	$ 107.85
Exercised (in dollars per share)	59.05
Forfeited (in dollars per share)	157.26
Outstanding at December 31, 2019	109.10	$ 107.85
Exercisable at December 31, 2019	109.32
Unvested at December 31, 2019	$ 52.57
Share awards, Weighted Average Remaining Contractual Term (in Years)
Outstanding at December 31, 2019	4 years 1 month 6 days
Exercisable at December 31, 2019	4 years 1 month 6 days
Unvested at December 31, 2019	2 years 10 months 24 days
Share awards, Aggregate Intrinsic Value
Outstanding at December 31, 2019	$ 29.9
Exercisable at December 31, 2019	29.5
Unvested at December 31, 2019	$ 0.4

Share-Based Compensation - Sh_2

Share-Based Compensation - Share Tracking Awards Plans - Benefit recognized (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
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax									$ 45.4	$ (26.4)	$ 73.5
Share-based compensation capitalized as part of inventory									0.7	0.7	0.4
STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax									(39.7)	(93.4)	27.1
Related income tax expense (benefit)									9	21.3	(10)
Share-based compensation expense, net of tax	$ 5.6	$ 1.2	$ (46)	$ 8.5	$ (10.3)	$ 24.8	$ 2.1	$ (88.7)	(30.7)	(72.1)	17.1
Cash payments on awards exercised during the period									7.6	75.7	63.4
Cost of product sales \| STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax									(1.7)	(4.7)	1.2
Research and development \| STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax									(8.2)	(17.9)	4.1
Selling, general and administrative \| STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax									$ (29.8)	$ (70.8)	$ 21.8

Share-Based Compensation - Empl

Share-Based Compensation - Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan	1 Months Ended
	Jun. 30, 2012shares
Share-based compensation expense
Offering period (in months)	6 months
Maximum percentage of compensation employees may contribute for ESPP (in percentage)	15.00%
Percentage of the lower of the fair market value of common stock on the first or last trading day of a given offering period (in percentage)	85.00%
Maximum number of shares each eligible employees may purchase in any given offering period (in shares)	4,000
Term of ESPP (in years)	20 years
Maximum number of shares authorized to be issued (in shares)	3,000,000

Stockholders' Equity - Earnings

Stockholders' Equity - 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
Numerator:
Net (loss) income	$ 52.6	$ 132.4	$ 205.1	$ (494.6)	$ 65.3	$ 106.5	$ 172.9	$ 244.5	$ (104.5)	$ 589.2	$ 417.9
Denominator:
Weighted average outstanding shares - basic (in shares)									43.8	43.5	44
Effect of dilutive securities:
Warrants (in shares)											0.1
Stock options, restricted stock units and employee stock purchase plan (in shares)										0.5	0.8
Weighted average shares - diluted (in shares)									43.8	44	44.9
Net (loss) income per common share:
Basic (in dollars per share)	$ 1.20	$ 3.02	$ 4.68	$ (11.32)	$ 1.50	$ 2.44	$ 4.01	$ 5.65	$ (2.39)	$ 13.54	$ 9.50
Diluted (in dollars per share)	$ 1.20	$ 3.01	$ 4.66	$ (11.32)	$ 1.48	$ 2.42	$ 3.98	$ 5.57	$ (2.39)	$ 13.39	$ 9.31
Stock options, restricted stock units, shares issuable under the ESPP and warrants excluded from calculation									7.2	4.7	3.3

Stockholders' Equity - Share Re

Stockholders' Equity - Share Repurchase (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	May 31, 2017	Apr. 30, 2017
Share Repurchase
Authorized aggregate repurchases of common stock				$ 250
May 2017 Accelerated Share Repurchase Agreement
Share Repurchase
Payment for cost of accelerated share repurchase agreement entered			$ 250
Repurchased shares of common stock		1.7
Repurchased additional shares of common stock	0.3

Stockholders' Equity - Sharehol

Stockholders' Equity - Shareholder Rights Plan (Details)	Jun. 30, 2008item$ / item
Shareholder Rights Plan
Purchase price of each Right, before the amendment and restatement of the Rights (in dollars per one one-thousandth of a share)	64.75
Purchase price of each Right, after the amendment and restatement of the Rights (in dollars per one one-thousandth of a share)	400
Number of shares of Series A Junior Participating Preferred Stock each Right entitles a holder to purchase \| item	0.001
Minimum ownership percentage in the outstanding shares of voting stock from the commencement of a tender offer that would result in the exercise of shares under one condition of the Agreement (as a percent)	15.00%

Stockholders' Equity - Accumula

Stockholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in accumulated other comprehensive loss, net of tax
Balance	$ 2,788.6	$ 2,101.8	$ 1,851.3
Net current-period other comprehensive (loss) income	(6.3)	11.7	(2.8)
Balance	2,780.4	2,788.6	2,101.8
Accumulated Other Comprehensive Loss
Changes in accumulated other comprehensive loss, net of tax
Balance	(7.9)	(19.6)	(16.8)
Other comprehensive (loss) income before reclassifications	(4.6)	10.3
Amounts reclassified from accumulated other comprehensive income	(1.7)	1.4
Net current-period other comprehensive (loss) income	(6.3)	11.7
Balance	(14.2)	(7.9)	(19.6)
Defined Benefit Pension Plan
Changes in accumulated other comprehensive loss, net of tax
Balance	12.3	0.2
Other comprehensive (loss) income before reclassifications	(10.6)	10.7
Amounts reclassified from accumulated other comprehensive income	(1.7)	1.4
Net current-period other comprehensive (loss) income	(12.3)	12.1
Balance		12.3	0.2
Foreign Currency Translation Losses
Changes in accumulated other comprehensive loss, net of tax
Balance	(17.9)	(17.9)
Balance	(17.9)	(17.9)	(17.9)
Unrealized Gains and (Losses) on Available-for-Sale Securities
Changes in accumulated other comprehensive loss, net of tax
Balance	(2.3)	(1.9)
Other comprehensive (loss) income before reclassifications	6	(0.4)
Net current-period other comprehensive (loss) income	6	(0.4)
Balance	$ 3.7	$ (2.3)	$ (1.9)

Income Taxes - Components of In

Income Taxes - Components of Income Tax (Benefit) Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 63.1	$ 136.6	$ 261.3
State	9.4	17.4	23.9
Total current	72.5	154	285.2
Deferred
Federal	(120.1)	12.7	67.2
State	(12.9)	3	(0.8)
Total deferred	(133)	15.7	66.4
Total income tax (benefit) expense	$ (60.5)	$ 169.7	$ 351.6

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of income taxes
Federal tax rate (as a percent)	21.00%	21.00%	35.00%
Federal taxes at the statutory rate	$ (34.7)	$ 159.4	$ 269.2
General business credits	(20.4)	(14.9)	(15.1)
Nondeductible compensation expense	6.3	2.1	1.8
Change in valuation allowance	(5.7)	11.2	17.5
Foreign income adjustment	5.1
State taxes, net of federal benefit	(4)	15.3	14.2
Deduction for foreign-derived intangible income	(3.3)	(3.3)
Deconsolidation of VIE	(1.9)
Other	(1.6)	3.6	1.3
Excess tax benefits from share-based compensation	(0.3)	(1.9)	(4.5)
Tax reform		(1.8)	71
Section 199 deduction			(22.8)
Nondeductible portion of DOJ settlement			19
Total income tax (benefit) expense	$ (60.5)	$ 169.7	$ 351.6

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Tax Asset (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Intangible assets	$ 192.4	$ 36.5
Share-based compensation	56	57
Impairments	25.8	23.1
SERP	10.1	10.7
NOLs	6.7	34.3
Reserves	6.5	9.3
Other	14.6	20.7
Total deferred tax assets	312.1	191.6
Deferred tax liabilities:
Plant and equipment principally due to differences in depreciation	(40.7)	(20.2)
Basic differences in foreign entities	0.6	(24.8)
Other	(5.4)	(8.3)
Net deferred tax asset before valuation allowance	266.6	138.3
Valuation allowance	(36.6)	(42.6)
Net deferred tax assets	$ 230	$ 95.7

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of beginning and ending balances of unrecognized tax benefits
Unrecognized tax benefits	$ 0	$ 0.5
Positions of unrecognized tax benefits, if realized, would impact the effective tax rate		0.3
Accrued interest expense related to uncertain tax positions	0	$ 0
Federal
Reconciliation of beginning and ending balances of unrecognized tax benefits
Net operating loss carryforwards	9.2
Foreign
Reconciliation of beginning and ending balances of unrecognized tax benefits
Net operating loss carryforwards	9.9
State
Reconciliation of beginning and ending balances of unrecognized tax benefits
Net operating loss carryforwards	$ 86.1

Employee Benefit Plans - SERP -

Employee Benefit Plans - SERP - General (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of beginning and ending balances of the projected benefit obligation
Period for benefit payments to retire eligible participants	1 year
Supplemental Executive Retirement Plan (SERP)
Supplemental Executive Retirement Plan Disclosure
Eligibility age	60 years
Number of months of salary taken as gross base for receipt of monthly payments	36 months
Vesting period of plan, when participants begin receiving payments	6 months
Reconciliation of beginning and ending balances of the projected benefit obligation
Projected benefit obligation at the beginning of the year	$ 46.8	$ 55.9
Service cost	2.2	2.4	$ 2.2
Interest cost	1.4	1.6	1.6
Benefits paid	(5.1)	(0.2)
Net actuarial loss (gain)	10.8	(12.9)
Projected benefit obligation at the end of the year	56.1	46.8	$ 55.9
Amount included in Other current liabilities	17.5	19.9
Amount included in Other non-current liabilities	$ 38.6	26.9
Reduction in benefit obligation		$ 7

Employee Benefit Plans - SERP_2

Employee Benefit Plans - SERP - Weighted-Average Assumptions (Details) - Supplemental Executive Retirement Plan (SERP)	Dec. 31, 2019	Dec. 31, 2018
Weighted-average assumptions used to measure SERP obligation:
Discount Rate (as a percent)	2.63%	3.92%
Salary Increases (as a percent)	4.00%	4.00%
Lump-sum distribution rate (as a percent)	3.00%	4.50%

Employee Benefit Plans - SERP_3

Employee Benefit Plans - SERP - Components of Net Periodic Pension Cost (Details) - Supplemental Executive Retirement Plan (SERP) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of net periodic pension cost
Service cost	$ 2.2	$ 2.4	$ 2.2
Interest cost	1.4	1.6	1.6
Amortization of prior service cost	1.5	1.5	1.5
Amortization of net actuarial gain	(2.2)	(0.2)	(0.6)
Settlement	(1.9)
Total	$ 1	$ 5.3	$ 4.7

Employee Benefit Plans - SERP_4

Employee Benefit Plans - SERP - Other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amounts included in accumulated other comprehensive loss expected to be recognized as components of net periodic pension cost
Amortization of prior service cost	$ 1.3
Supplemental Executive Retirement Plan (SERP)
Amounts relating to the SERP that have been recognized in other comprehensive (loss) income
Net actuarial (loss) gain	(12.9)	$ 12.7	$ (3.2)
Prior service cost (benefit)	1.5	1.5	1.5
Settlement	(1.9)
Total recognized in other comprehensive (loss) income	(13.3)	14.2	(1.7)
Tax benefit (expense)	1	(2.1)	0.6
Total, net of tax	(12.3)	12.1	(1.1)
Accumulated other comprehensive loss that have not yet been recognized as a component of net periodic pension cost
Net actuarial gain	(4.5)	(19.3)	(6.6)
Prior service cost	3.3	4.7	6.2
Total included in accumulated other comprehensive loss	(1.2)	(14.6)	(0.4)
Tax expense	$ 1.2	2.3	0.2
Total, net of tax		$ (12.3)	$ (0.2)

Employee Benefit Plans - Future

Employee Benefit Plans - Future estimated benefit payments (Details) - Supplemental Executive Retirement Plan (SERP) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Supplemental Executive Retirement Plan Disclosure
Accumulated benefit obligation	$ 47.4	$ 39.8
Future estimated benefit payments
2020	17.5
2023	6.2
2024	16.1
Thereafter	44.8
Total future estimated benefit payments	$ 84.6

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Retirement Plan (Details)	12 Months Ended
Employee Benefit Plans - Employee Retirement Plan (Details)	Dec. 31, 2019item
Employee Retirement Plan
Employer's matching contribution, percentage of participant's elected salary deferral	40.00%
Period of service for vesting of matching contributions	3 years
Annual increments for vesting in employer's matching contribution	0.33
Period over which the matching contribution vest annually	3 years

Commitments and Contingencies_2

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Future minimum lease payments under non-cancelable operating leases
2020	$ 2.1
2021	1.7
2022	1
2023	0.7
2024	0.4
Thereafter	0.6
Total	6.5
Total rent expense	$ 4.9	$ 4.2	$ 4.8

Commitments and Contingencies -

Commitments and Contingencies - Milestone Payments and Royalty Obligations (Details) - USD ($)	Jan. 24, 2019	Nov. 30, 2017	Nov. 30, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assignment and License Agreements
Net product sales						$ 1,448,800,000	$ 1,627,800,000	$ 1,725,300,000
Marketing approval in the United States
Assignment and License Agreements
Milestone payment to be made upon marketing approval	$ 250,000,000
Marketing approval in any of Japan, France, Italy, the United Kingdom, Spain or Germany
Assignment and License Agreements
Milestone payment to be made upon marketing approval	$ 150,000,000
Orenitram
Assignment and License Agreements
Net product sales						225,300,000	205,100,000	185,800,000
Adcirca
Assignment and License Agreements
Net product sales						107,200,000	323,700,000	419,700,000
Unituxin
Assignment and License Agreements
Net product sales						113,700,000	84,800,000	76,000,000
Remodulin
Assignment and License Agreements
Net product sales						$ 587,000,000	$ 599,000,000	$ 670,900,000
Supernus Pharmaceuticals, Inc. \| Orenitram
Assignment and License Agreements
Scaling royalties percentage						single digit
Eli Lilly and Company \| Adcirca
Assignment and License Agreements
Royalty as a percentage of net sales		5.00%			10.00%
Royalty expenses					$ 325,000
Net product sales					$ 1,000,000
Scripps Research Institute \| Unituxin
Assignment and License Agreements
Royalty as a percentage of net sales						1.00%
Medtronic, Inc \| Remodulin
Assignment and License Agreements
Royalty as a percentage of net sales						10.00%
DEKA Research & Development Corp \| RemUnity
Assignment and License Agreements
Scaling royalties percentage						single-digit
Samumed LLC \| LNG01 (formerly SM04646)
Assignment and License Agreements
Maximum potential milestone payment to be made				$ 340,000,000
MannKind Corporation \| Treprostinil
Assignment and License Agreements
Maximum potential milestone payment to be made						$ 50,000,000
Milestone Payment for product development						$ 25,000,000
Arena Pharmaceuticals, Inc. \| Ralinepag \| Marketing approval in the United States
Assignment and License Agreements
Milestone payment to be made upon marketing approval			$ 250,000,000
Arena Pharmaceuticals, Inc. \| Ralinepag \| Marketing approval in any of Japan, France, Italy, the United Kingdom, Spain or Germany
Assignment and License Agreements
Milestone payment to be made upon marketing approval			$ 150,000,000

Segment Information - General (

Segment Information - General (Details) $ in Millions	3 Months Ended								12 Months Ended
Segment Information - General (Details) $ in Millions	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Net product sales, cost of product sales and gross profit by product
Number of operating segments \| segment									1
Net product sales									$ 1,448.8	$ 1,627.8	$ 1,725.3
Cost of product sales	$ 28.8	$ 33	$ 26.7	$ 29.1	$ 31.9	$ 51.9	$ 61.7	$ 53.2	117.6	198.7	105.7
Gross profit									1,331.2	1,429.1	1,619.6
Remodulin
Net product sales, cost of product sales and gross profit by product
Net product sales									587	599	670.9
Cost of product sales									21.1	14.1	15.9
Gross profit									565.9	584.9	655
Tyvaso
Net product sales, cost of product sales and gross profit by product
Net product sales									415.6	415.2	372.9
Cost of product sales									19.6	17.3	18.5
Gross profit									396	397.9	354.4
Orenitram
Net product sales, cost of product sales and gross profit by product
Net product sales									225.3	205.1	185.8
Cost of product sales									15	13.2	15.3
Gross profit									210.3	191.9	170.5
Unituxin
Net product sales, cost of product sales and gross profit by product
Net product sales									113.7	84.8	76
Cost of product sales									15.7	14.3	12.9
Gross profit									98	70.5	63.1
Adcirca
Net product sales, cost of product sales and gross profit by product
Net product sales									107.2	323.7	419.7
Cost of product sales									46.2	139.8	43.1
Gross profit									$ 61	$ 183.9	$ 376.6

Segment Information - Geographi

Segment Information - Geographic Information (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
Revenues from external customers by geographic area
Total revenues	$ 311.1	$ 401.5	$ 373.6	$ 362.6	$ 381.4	$ 412.7	$ 444.5	$ 389.2	$ 1,448.8	$ 1,627.8	$ 1,725.3
Property, Plant and Equipment, Net	738.5				699.7				738.5	699.7	545.7
United States
Revenues from external customers by geographic area
Total revenues									1,323.2	1,528.2	1,536.8
Property, Plant and Equipment, Net	723.1				684				723.1	684	544.5
Rest-of-World
Revenues from external customers by geographic area
Total revenues									125.6	99.6	188.5
Property, Plant and Equipment, Net	$ 15.4				$ 15.7				$ 15.4	$ 15.7	$ 1.2

Segment Information - Concentra

Segment Information - Concentration Risk (Details) - Distributor	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Information
Number of distributors	2
Net revenues \| Customer concentration \| Customer one
Segment Information
Concentration risk, percentage	54.00%	51.00%	46.00%
Net revenues \| Customer concentration \| Customer two
Segment Information
Concentration risk, percentage	22.00%	18.00%	15.00%

Quarterly Financial Informati_3

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
Total revenues	$ 311.1	$ 401.5	$ 373.6	$ 362.6	$ 381.4	$ 412.7	$ 444.5	$ 389.2	$ 1,448.8	$ 1,627.8	$ 1,725.3
Cost of product sales	28.8	33	26.7	29.1	31.9	51.9	61.7	53.2	117.6	198.7	105.7
Gross profit	282.3	368.5	346.9	333.5	349.5	360.8	382.8	336
Net income (loss)	$ 52.6	$ 132.4	$ 205.1	$ (494.6)	$ 65.3	$ 106.5	$ 172.9	$ 244.5	$ (104.5)	$ 589.2	$ 417.9
Net income (loss) per share-basic (in dollars per share)	$ 1.20	$ 3.02	$ 4.68	$ (11.32)	$ 1.50	$ 2.44	$ 4.01	$ 5.65	$ (2.39)	$ 13.54	$ 9.50
Net income (loss) per share-diluted (in dollars per share)	$ 1.20	$ 3.01	$ 4.66	$ (11.32)	$ 1.48	$ 2.42	$ 3.98	$ 5.57	$ (2.39)	$ 13.39	$ 9.31
STAP awards
Share-based compensation expense (benefit) charged to operating expenses, net of tax	$ 5.6	$ 1.2	$ (46)	$ 8.5	$ (10.3)	$ 24.8	$ 2.1	$ (88.7)	$ (30.7)	$ (72.1)	$ 17.1

Litigation (Details)

Litigation (Details) - USD ($) $ in Millions	Dec. 19, 2017	Dec. 31, 2017
Litigation
Cash paid for settlement of loss contingency		$ 210
U.S Department of Justice
Litigation
Cash paid for settlement of loss contingency	$ 210
Loss contingency accrual		$ 210
Office of Inspector General
Litigation
Period for maintaining corporate compliance program and to undertake defined corporate integrity obligations	5 years

Arena License Agreement (Detail

Arena License Agreement (Details) - USD ($) $ in Millions	Jan. 24, 2019	Mar. 31, 2019
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Upfront payment		$ 800
Marketing approval in the United States
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Milestone payment to be made upon marketing approval	$ 250
Marketing approval in any of Japan, France, Italy, the United Kingdom, Spain or Germany
Collaborative Arrangements and Non-collaborative Arrangement Transactions
Milestone payment to be made upon marketing approval	$ 150

Schedule II-Valuation and Qua_2

Schedule II-Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in valuation and qualifying accounts
Balance at Beginning of Year	$ 42.6
Balance at End of Year	36.6	$ 42.6
Valuation Allowance on Deferred Tax Assets
Change in valuation and qualifying accounts
Balance at Beginning of Year	42.6	16.9	$ 4.7
Additions Charged to Expense	1.9	14.9	11.8
Other Additions	0.9	11	1.6
Deductions	(8.8)	(0.2)	(1.2)
Balance at End of Year	36.6	42.6	16.9
Inventory Reserves
Change in valuation and qualifying accounts
Balance at Beginning of Year	26	25.1	17.5
Additions Charged to Expense	8.4	11.7	12.1
Deductions	(13.5)	(10.8)	(4.5)
Balance at End of Year	$ 20.9	$ 26	$ 25.1