United Therapeutics (UTHR) 10-Q 5 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 28, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	0-26301
Entity Registrant Name	United Therapeutics Corporation
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001082554
Amendment Flag	false
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 $0.01 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		44,796,404

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 832.3	$ 738.7
Marketable investments	899	1,096.3
Accounts receivable, no allowance for 2021 and 2020	141.1	157.4
Inventories, net	92.2	86.5
Other current assets	49.7	88.3
Total current assets	2,014.3	2,167.2
Marketable investments	1,433.5	1,149.6
Goodwill and other intangible assets, net	44.7	158.1
Property, plant, and equipment, net	713.7	731.6
Deferred tax assets, net	263.6	238.6
Other non-current assets	171.2	169.9
Total assets	4,641	4,615
Current liabilities:
Accounts payable and accrued expenses	165	187
Share tracking awards plan	107.1	96.8
Other current liabilities	30.3	39.5
Total current liabilities	302.4	323.3
Line of credit (non-current)	800	800
Other non-current liabilities	93.2	96.5
Total liabilities	1,195.6	1,219.8
Stockholders’ equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued	0	0
Common stock, par value $.01, 245,000,000 shares authorized, 71,407,834 and 71,126,314 shares issued, and 44,788,618 and 44,507,098 shares outstanding at March 31, 2021 and December 31, 2020, respectively	0.7	0.7
Additional paid-in capital	2,173.2	2,148.7
Accumulated other comprehensive loss	(16.8)	(14.2)
Treasury stock, 26,619,216 shares at March 31, 2021 and December 31, 2020	(2,579.2)	(2,579.2)
Retained earnings	3,867.5	3,839.2
Total stockholders’ equity	3,445.4	3,395.2
Total liabilities and stockholders’ equity	$ 4,641	$ 4,615

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 0	$ 0
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
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	71,407,834	71,126,314
Common stock, shares outstanding	44,788,618	44,507,098
Treasury stock (in shares)	26,619,216	26,619,216

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Total revenues	$ 379.1	$ 356.3
Revenue from contract with customer, product and service	Net product sales	Net product sales
Operating expenses:
Cost of product sales	$ 23	$ 23.4
Cost, product and service	Net product sales	Net product sales
Research and development	$ 303.7	$ 73.2
Selling, general, and administrative	117.2	93
Total operating expenses	443.9	189.6
Operating (loss) income	(64.8)	166.7
Interest income	4.7	10
Interest expense	(4.6)	(8.2)
Other income, net	97.2	8.7
Impairments of investments in privately-held companies	0	(5.6)
Total other income, net	97.3	4.9
Income before income taxes	32.5	171.6
Income tax expense	(4.2)	(33.9)
Net income	$ 28.3	$ 137.7
Net income per common share:
Basic (in dollars per share)	$ 0.63	$ 3.14
Diluted (in dollars per share)	$ 0.61	$ 3.12
Weighted average number of common shares outstanding:
Basic (in shares)	44.6	43.9
Diluted (in shares)	46.4	44.1
Net product sales
Revenues:
Total revenues	$ 379.1	$ 356.3

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Comprehensive income:
Net income	$ 28.3	$ 137.7
Defined benefit pension plan:
Actuarial gain arising during period, net of tax	0.2	0.2
Amortization of prior service cost included in net periodic pension cost, net of tax	0.1	0.3
Total defined benefit pension plan, net of tax	0.3	0.5
Unrealized (loss) gain on available-for-sale securities, net of tax	(2.9)	10.2
Other comprehensive (loss) income, net of tax	(2.6)	10.7
Comprehensive income	$ 25.7	$ 148.4

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Treasury Stock	Retained Earnings	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, AdjustmentRetained Earnings
Balance at Dec. 31, 2019	$ 2,780.4	$ 0.7	$ 2,047.9	$ (14.2)	$ (2,579.2)	$ 3,325.2	$ (0.8)	$ (0.8)
Balance (in shares) at Dec. 31, 2019		70.5
Increase (Decrease) in Stockholders' Equity
Net income	137.7					137.7
Unrealized (losses) gains on available-for-sale securities	10.2			10.2
Defined benefit pension plan	0.5			0.5
Shares issued under employee stock purchase plan	2.5		2.5
Restricted stock units (RSUs) withheld for taxes	(3.4)		(3.4)
Common stock issued for RSUs vested (in shares)		0.1
Exercise of stock options	0.7		0.7
Share-based compensation	20.7		20.7
Balance at Mar. 31, 2020	2,948.5	$ 0.7	2,068.4	(3.5)	(2,579.2)	3,462.1
Balance (in shares) at Mar. 31, 2020		70.6
Balance at Dec. 31, 2020	3,395.2	$ 0.7	2,148.7	(14.2)	(2,579.2)	3,839.2
Balance (in shares) at Dec. 31, 2020		71.1
Increase (Decrease) in Stockholders' Equity
Net income	28.3					28.3
Unrealized (losses) gains on available-for-sale securities	(2.9)			(2.9)
Defined benefit pension plan	0.3			0.3
Shares issued under employee stock purchase plan	2.8		2.8
Shares issued under employee stock purchase plan (in shares)		0.1
Restricted stock units (RSUs) withheld for taxes	(10.2)		(10.2)
Common stock issued for RSUs vested (in shares)		0.1
Exercise of stock options	17.5		17.5
Exercise of stock options (in shares)		0.1
Share-based compensation	14.4		14.4
Balance at Mar. 31, 2021	$ 3,445.4	$ 0.7	$ 2,173.2	$ (16.8)	$ (2,579.2)	$ 3,867.5
Balance (in shares) at Mar. 31, 2021		71.4

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income	$ 28.3	$ 137.7
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12.5	12.4
Share-based compensation expense	40.1	30.8
Impairments of investments in privately-held companies	0	5.6
Intangible asset impairment charges	113.4	0
Impairments of property, plant, and equipment	17	0
Realized gain on sale of equity securities	(91.9)	(2)
Other	(8.5)	(22.8)
Changes in operating assets and liabilities:
Accounts receivable	16.3	1.7
Inventories	(2.2)	6.1
Accounts payable and accrued expenses	(25)	(18.8)
Other assets and liabilities	(10.2)	63.9
Net cash provided by operating activities	89.8	214.6
Cash flows from investing activities:
Purchases of property, plant, and equipment	(10.6)	(13)
Purchases of available-for-sale investments	(559)	(479.2)
Maturities of available-for-sale investments	454.4	435.4
Sales of available-for-sale investments	0	16
Sales of investments in equity securities	108.9	13.2
Net cash used in investing activities	(6.3)	(27.6)
Cash flows from financing activities:
Repayment of line of credit	0	(50)
Proceeds from the exercise of stock options	17.5	0.7
Proceeds from the issuance of stock under employee stock purchase plan	2.8	2.5
Restricted stock units withheld for taxes	(10.2)	(3.4)
Net cash provided by (used in) financing activities	10.1	(50.2)
Net increase in cash and cash equivalents	93.6	136.8
Cash and cash equivalents, beginning of period	738.7	738.4
Cash and cash equivalents, end of period	832.3	875.2
Supplemental cash flow information:
Cash paid for interest	4	7.5
Cash received for income taxes	(1.6)	(8.7)
Non-cash investing and financing activities:
Non-cash additions to property, plant, and equipment	$ 5.1	$ 5.4

Organization and Business Descr

Organization and Business Description	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Business Description	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 ® (treprostinil) Injection ( Remodulin ), Tyvaso ® (treprostinil) Inhalation Solution ( Tyvaso ), Orenitram ® (treprostinil) Extended-Release Tablets ( Orenitram ), Unituxin ® (dinutuximab) Injection ( Unituxin ), and Adcirca ® (tadalafil) Tablets ( Adcirca ). Our only significant revenues outside the United States are derived from sales of Remodulin in Europe. 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.

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with the rules and regulations of the U.S. Securities and Exchange Commission ( SEC ) for interim financial information. Accordingly, they do not include all of the information required by U.S. generally accepted accounting principles ( GAAP ) for complete financial statements. Certain prior year amounts have been reclassified to conform to the current year presentation. In the operating activities section of our consolidated statements of cash flows, we reclassified a portion of the prior period amount within other assets and liabilities to the line item realized gain on sale of equity securities to conform with the current period presentation. In the investing activities section of our consolidated statements of cash flows, we reclassified the prior period amount within sales/maturities of available-for-sale investments to the line items maturities of available-for-sale investments and sales of available-for-sale investments to conform with the current period presentation. These consolidated financial statements should be read in conjunction with our audited consolidated financial statements and the accompanying notes to our consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2020, as filed with the SEC on February 24, 2021. In our management’s opinion, the accompanying consolidated financial statements contain all adjustments, including normal, recurring adjustments, necessary to fairly present our financial position as of March 31, 2021 and December 31, 2020, and our statements of operations, comprehensive income, stockholders’ equity, and cash flows for the three-month periods ended March 31, 2021 and 2020. Interim results are not necessarily indicative of results for an entire year. Recently Issued Accounting Standards Accounting Standards Adopted During the Period In December 2019, the Financial Accounting Standards Board ( FASB ) issued Accounting Standards Update ( ASU ) No. 2019-12, Simplifying the Accounting for Income Taxes ( ASU 2019-12 ) , which simplifies the accounting for income taxes by removing certain exceptions to the general principles of Topic 740, Income Taxes, and also improves consistency of application by clarifying and amending existing guidance. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020. We adopted the new standard on January 1, 2021, with no material impact on our financial statements. In January 2020, the FASB issued ASU No. 2020-01, Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815)-Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 (a consensus of the Emerging Issues Task Force) ( ASU 2020-01 ), which addresses the accounting for the transition into and out of the equity method and measuring certain purchased options and forward contracts to acquire investments. ASU 2020-01 is effective for fiscal years beginning after December 15, 2020. We adopted the new standard on January 1, 2021, with no material impact on our financial statements. Accounting Standards Not Yet Adopted In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ( ASU 2020-04 ), which provides optional expedients and exceptions to lessen the burden of accounting for contract modifications and hedging relationships that reference LIBOR or other reference rates that could be discontinued due to reference rate reform. ASU 2020-04 became effective immediately and may be applied through December 31, 2022. We are currently evaluating the impact of the expedients and exceptions of this new standard on our accounting for our credit agreement, which references LIBOR.

Investments

Investments	3 Months Ended
	Mar. 31, 2021
Investments [Abstract]
Investments	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): As of March 31, 2021 Amortized Gross Gross Fair U.S. government and agency securities $ 1,911.5 $ 7.5 $ (0.4) $ 1,918.6 Corporate debt securities 345.6 2.1 (0.1) 347.6 Total $ 2,257.1 $ 9.6 $ (0.5) $ 2,266.2 Reported under the following captions on our consolidated balance sheets: Current marketable investments $ 832.7 Non-current marketable investments 1,433.5 Total $ 2,266.2 As of December 31, 2020 Amortized Gross Gross Fair U.S. government and agency securities $ 1,902.4 $ 9.8 $ (0.1) $ 1,912.1 Corporate debt securities 331.2 3.2 — 334.4 Total $ 2,233.6 $ 13.0 $ (0.1) $ 2,246.5 Reported under the following captions on our consolidated balance sheets: Cash and cash equivalents $ 79.0 Current marketable investments 1,017.9 Non-current marketable investments 1,149.6 Total $ 2,246.5 The following table summarizes the contractual maturities of available-for-sale debt securities (in millions). Actual maturities may differ from contractual maturities because the issuers of certain of these debt securities have the right to call the securities or prepay their obligations under the securities with or without penalties. As of March 31, 2021 Amortized Cost Fair Value Due within one year $ 829.1 $ 832.7 Due in one to three years 1,428.0 1,433.5 Total $ 2,257.1 $ 2,266.2 Investments in Equity Securities with Readily Determinable Fair Values We held investments in equity securities with readily determinable fair values of $66.3 million and $78.4 million as of March 31, 2021 and December 31, 2020, respectively, which are included in current marketable investments on our consolidated balance sheets. Changes in the fair value of publicly traded equity securities are recorded on our consolidated statements of operations within other income, net . Refer to Note 4 —Fair Value Measurements . During the three months ended March 31, 2021, we sold our investment in a publicly-traded company. We received $108.9 million in cash from the sale of the investment and realized a gain of $91.9 million. The gain was recorded within other income, net on our consolidated statements of operations. Investments in Privately-Held Companies As of March 31, 2021 and December 31, 2020, we maintained non-controlling equity investments in privately-held companies of $84.8 million, in the aggregate. We measure these investments 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, and adjusted for any observable price changes. 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 . During the three months ended March 31, 2020, one of these privately-held companies raised additional capital by issuing equity securities similar to the security that we hold at an increased valuation, which resulted in an increase of $22.5 million in the value of our investment. The gain was recorded within other income, net on our consolidated statements of operations for the three months ended March 31, 2020. During the three months ended March 31, 2020, we observed an indicator of impairment for our investments in two of these companies, which caused us to recognize impairment charges of $5.6 million. These impairment charges were recorded within impairments of investments in privately-held companies on our consolidated statements of operations for the three months ended March 31, 2020. Variable Interest Entity Unconsolidated Variable Interest Entity In November 2019, we entered into a supply agreement with an affiliate of DEKA Research & Development Corporation ( DEKA ) to manufacture and supply the Remunity ® Pump to us. Under the terms of the supply agreement, we will reimburse all of the affiliate’s costs to manufacture and supply the Remunity Pump. We determined that the affiliate is a variable interest entity as we are currently the only customer of the affiliate and the affiliate currently relies on our reimbursement of its costs to sustain its operations. We have determined we are not the primary beneficiary of the affiliate as we do not have the power to direct or control its significant activities related to the manufacturing of medical devices. Accordingly, we have not consolidated the affiliate’s results of operations and financial position with ours. As of March 31, 2021 and December 31, 2020, our consolidated balance sheets included $12.3 million and $11.7 million of assets, respectively, related to the supply agreement. As of March 31, 2021 and December 31, 2020, our consolidated balance sheets included a $4.6 million and $24.0 million liability, respectively, for our obligation to reimburse costs related to the supply agreement. While the terms of the supply agreement expose us to various future risks of loss given our responsibility to reimburse all costs incurred by the affiliate to manufacture and supply the Remunity Pump, we believe that our maximum exposure to loss as of March 31, 2021 as a result of our involvement with the affiliate is $12.3 million, the amount of assets related to the supply agreement noted above.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value MeasurementsWe account for certain assets and liabilities at fair value and classify these assets and liabilities within the fair value hierarchy (Level 1, Level 2, or Level 3). Our other current assets and other current liabilities have fair values that approximate their carrying values. Assets and liabilities subject to fair value measurements are as follows (in millions): As of March 31, 2021 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 390.2 $ — $ — $ 390.2 Time deposits (2) 88.0 — — 88.0 U.S. government and agency securities (3) — 1,918.6 — 1,918.6 Corporate debt securities (3) — 347.6 — 347.6 Equity securities (4) 66.3 — — 66.3 Contingent consideration (5) — — 6.0 6.0 Total assets $ 544.5 $ 2,266.2 $ 6.0 $ 2,816.7 Liabilities Contingent consideration (6) — — 15.1 15.1 Total liabilities $ — $ — $ 15.1 $ 15.1 As of December 31, 2020 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 323.1 $ — $ — $ 323.1 U.S. government and agency securities (3) — 1,912.1 — 1,912.1 Corporate debt securities (3) — 334.4 — 334.4 Equity securities (4) 78.4 — — 78.4 Contingent consideration (5) — — 4.1 4.1 Total assets $ 401.5 $ 2,246.5 $ 4.1 $ 2,652.1 Liabilities Contingent consideration (6) — — 17.1 17.1 Total liabilities $ — $ — $ 17.1 $ 17.1 (1) Included in cash and cash equivalents on our consolidated balance sheets. (2) Included in cash and cash equivalents 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 3— 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 three months ended March 31, 2021 and March 31, 2020, we recognized $96.8 million of net unrealized and realized gains and $6.1 million of net unrealized and realized losses, respectively, on these securities. We recorded these gains and losses on our consolidated statements of operations within other income, net . Refer to Note 3— Investments—Marketable Investments—Investments in Equity Securities with Readily Determinable Fair Values . (5) Included in other current and other non-current assets on our consolidated balance sheets. We estimated the fair value of contingent consideration using a Monte Carlo simulation. The Monte Carlo simulation incorporates Level 3 inputs including price volatility of peer company stocks and the probability of completing certain milestones during a specified period of time. The fair value of our contingent consideration assets increased by $1.9 million from December 31, 2020 to March 31, 2021. The gain was recorded within other income, net on our consolidated statements of operations. (6) Included in non-current liabilities on our consolidated balance sheets. The fair value of our contingent consideration obligations 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 our contingent consideration obligations for the three months ended March 31, 2021 was the result of our decision in January 2021 to discontinue our research and development efforts related to biomechanical lungs. As a result of the decision, we de-recognized $2.0 million of a related contingent consideration liability during the first quarter of 2021. The gain was recorded within research and development on our consolidated statements of operations. 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. Refer to Note 3— Investments . 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.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
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): March 31, 2021 December 31, 2020 Raw materials $ 16.0 $ 18.4 Work-in-progress 31.2 29.5 Finished goods 45.0 38.6 Total inventories $ 92.2 $ 86.5

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill and other intangible assets comprise the following (in millions): As of March 31, 2021 As of December 31, 2020 Gross Accumulated Net Gross Accumulated Net Goodwill $ 28.0 $ — $ 28.0 $ 28.0 $ — $ 28.0 Other intangible assets: Technology, patents, and trade names 6.7 (5.5) 1.2 6.7 (5.5) 1.2 In-process research and development (1) (2) 15.5 — 15.5 128.9 — 128.9 Total $ 50.2 $ (5.5) $ 44.7 $ 163.6 $ (5.5) $ 158.1 (1) In March 2021, we decided to discontinue the U.S. development of Trevyent ® , due to written comments provided by the FDA in February 2021. The FDA provided these written comments following a meeting between us and the FDA to discuss our planned resubmission of the New Drug Application for Trevyent in light of a Complete Response Letter issued by the FDA in April 2020. We determined this to be a potential indicator of impairment of our in-process research and development ( IPR&D ) asset related to Trevyent, which had a carrying value of $107.3 million as of December 31, 2020. Based on our decision to discontinue the U.S. development of Trevyent, we fully impaired the IPR&D asset related to Trevyent during the first quarter of 2021. The $107.3 million impairment charge was recorded within research and development on our consolidated statements of operations. (2) In January 2021, we decided to discontinue our research and development efforts related to biomechanical lungs. As a result of the decision, we fully impaired the IPR&D asset related to these efforts, which had a carrying value of $6.1 million, during the first quarter of 2021. The impairment charge was recorded within research and development on our consolidated statements of operations.

Property, Plant, and Equipment

Property, Plant, and Equipment	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant, and Equipment	Property, Plant, and Equipment Property, plant, and equipment ( PP&E ) consists of the following (in millions): March 31, 2021 December 31, 2020 Land and land improvements $ 75.0 $ 74.9 Buildings, building improvements, and leasehold improvements 601.7 593.6 Buildings under construction 45.6 47.4 Furniture, equipment, and vehicles 308.6 325.0 Subtotal 1,030.9 1,040.9 Less—accumulated depreciation (317.2) (309.3) Property, plant, and equipment, net $ 713.7 $ 731.6 In 2019, we completed construction of a new cell culture and purification facility. During the first quarter of 2021, we decided to repurpose this facility to produce autologous cells that we intend to use to cellularize lung scaffolds for clinical studies. The decision to repurpose this facility was an indicator of impairment of the facility which we evaluated during the first quarter of 2021. Based on our impairment assessment, we recorded an $11.6 million impairment charge on the net book value of this facility during the first quarter of 2021. During the first quarter of 2021, we recorded $17.0 million of PP&E impairment charges in the aggregate, of which $15.5 million was recorded within research and development on our consolidated statements of operations and $1.5 million was recorded within selling, general, and administrative on our consolidated statements of operations.

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt Credit Agreement In June 2018, we entered into a credit agreement (the 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 December 2020, we extended the maturity date of the Credit Agreement by one year, to December 2025. At our option, amounts borrowed under the 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 Credit Agreement). To date, we have elected to calculate interest on the outstanding balance at LIBOR plus an applicable margin. As of March 31, 2021 and December 31, 2020, our outstanding aggregate principal balance under the Credit Agreement was $800.0 million, all of which was classified as a non-current liability because we do not intend to repay any portion of this amount within one year. The Credit Agreement contains customary events of default and customary affirmative and negative covenants. As of March 31, 2021, we were in compliance with these covenants. Lung Biotechnology PBC is our only subsidiary that guarantees our obligations under the 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 Credit Agreement, we capitalized debt issuance costs, which are being amortized to interest expense over the contractual term of the Credit Agreement. As of March 31, 2021, $2.4 million was recorded in other current assets and $8.7 million in other non-current assets on our consolidated balance sheets. The interest expense reported on our consolidated statements of operations for the three months ended March 31, 2021 and 2020, related to our borrowings under the Credit Agreement.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	Share-Based Compensation As of March 31, 2021, 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 (the 2015 Plan ). The 2015 Plan provides for the issuance of up to 10,000,000 shares of our common stock pursuant to awards granted under the 2015 Plan. 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 and Restricted Stock Units below. 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 below. We discontinued the issuance of STAP awards in June 2015. 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 below. The following table reflects the components of share-based compensation expense recognized in our consolidated statements of operations (in millions): Three Months Ended 2021 2020 Stock options $ 8.3 $ 16.4 Restricted stock units 5.7 4.0 STAP awards 25.7 10.1 Employee stock purchase plan 0.4 0.3 Total share-based compensation expense before tax $ 40.1 $ 30.8 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. The following weighted average assumptions were used in estimating the fair value of stock options granted to employees during the three months ended March 31, 2021 and 2020: March 31, 2021 March 31, 2020 Expected term of awards (in years) 6.0 6.0 Expected volatility 32.7 % 32.4 % Risk-free interest rate 1.1 % 0.8 % Expected dividend yield — % — % A summary of the activity and status of stock options under our equity incentive plans during the three-month period ended March 31, 2021 is presented below: Number of Weighted Weighted Aggregate Outstanding at January 1, 2021 7,680,194 $ 126.27 Granted 14,603 164.10 Exercised (132,789) 131.83 Forfeited/canceled (213) 146.03 Outstanding at March 31, 2021 7,561,795 $ 126.24 5.4 $ 311.5 Exercisable at March 31, 2021 5,801,938 $ 125.75 5.1 $ 242.2 Unvested at March 31, 2021 1,759,857 $ 127.88 6.1 $ 69.3 The weighted average fair value of a stock option granted during each of the three-month periods ended March 31, 2021 and March 31, 2020, was $54.63 and $29.85, respectively. These stock options have an aggregate grant date fair value of $0.8 million and $0.5 million, respectively. The total grant date fair value of stock options that vested during the three-month periods ended March 31, 2021 and March 31, 2020 was $48.1 million and $69.8 million, respectively. Total share-based compensation expense related to stock options is recorded as follows (in millions): Three Months Ended 2021 2020 Cost of product sales $ 0.1 $ 0.2 Research and development 0.2 0.9 Selling, general, and administrative 8.0 15.3 Share-based compensation expense before taxes 8.3 16.4 Related income tax benefit (0.3) (3.7) Share-based compensation expense, net of taxes $ 8.0 $ 12.7 As of March 31, 2021, unrecognized compensation cost related to stock options was $41.1 million. Unvested outstanding stock options as of March 31, 2021 had a weighted average remaining vesting period of 1.9 years. Stock option exercise data is summarized below (dollars in millions): Three Months Ended 2021 2020 Number of options exercised 132,789 13,500 Cash received $ 17.5 $ 0.7 Total intrinsic value of options exercised $ 4.7 $ 0.6 Restricted Stock Units 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 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 the three-month period ended March 31, 2021 is presented below: Number of Weighted Unvested at January 1, 2021 440,528 $ 102.40 Granted 171,244 164.16 Vested (181,297) 104.68 Forfeited/canceled (6,311) 116.70 Unvested at March 31, 2021 424,164 $ 126.15 Total share-based compensation expense related to restricted stock units is recorded as follows (in millions): Three Months Ended 2021 2020 Cost of product sales $ 0.5 $ 0.3 Research and development 1.8 1.4 Selling, general, and administrative 3.4 2.3 Share-based compensation expense before taxes 5.7 4.0 Related income tax benefit (1.3) (0.9) Share-based compensation expense, net of taxes $ 4.4 $ 3.1 As of March 31, 2021, unrecognized compensation cost related to the grant of restricted stock units was $50.0 million. Unvested outstanding restricted stock units as of March 31, 2021 had a weighted average remaining vesting period of 2.4 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. We discontinued the issuance of STAP awards in June 2015. The aggregate STAP liability balance was $107.1 million and $96.8 million at March 31, 2021 and December 31, 2020, respectively, all of which was classified as a current liability on our consolidated balance sheets. 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. The table below includes the weighted average assumptions used to measure the fair value of the outstanding STAP awards: March 31, 2021 March 31, 2020 Expected term of awards (in years) 1.6 2.0 Expected volatility 33.3 % 32.5 % Risk-free interest rate 0.2 % 0.2 % Expected dividend yield — % — % The closing price of our common stock was $167.27 and $94.83 on March 31, 2021 and March 31, 2020, respectively. The closing price of our common stock was $151.79 on December 31, 2020. A summary of the activity and status of STAP awards during the three-month period ended March 31, 2021 is presented below: Number of Weighted Weighted Aggregate Outstanding at January 1, 2021 2,121,860 $ 118.48 Granted — — Exercised (194,933) 90.06 Forfeited/canceled (562) 145.30 Outstanding at March 31, 2021 1,926,365 $ 121.35 3.2 $ 88.6 Exercisable at March 31, 2021 1,916,365 $ 121.71 3.2 $ 87.4 Unvested at March 31, 2021 10,000 $ 52.57 1.7 $ 1.2 Share-based compensation expense recognized in connection with STAP awards is as follows (in millions): Three Months Ended 2021 2020 Cost of product sales $ 1.1 $ 0.7 Research and development 4.3 2.2 Selling, general, and administrative 20.3 7.2 Share-based compensation expense before taxes 25.7 10.1 Related income tax benefit (4.9) (2.3) Share-based compensation expense, net of taxes $ 20.8 $ 7.8 Cash paid to settle STAP exercises during the three-month periods ended March 31, 2021 and March 31, 2020 was $15.4 million and $3.0 million, respectively. Employee Stock Purchase Plan 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 expires in June 2032 and limits the aggregate number of shares that can be issued under the ESPP to 3.0 million.

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share Basic earnings per common share is computed by dividing net 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. The components of basic and diluted earnings per common share comprised the following (in millions, except per share amounts): Three Months Ended 2021 2020 Numerator: Net income $ 28.3 $ 137.7 Denominator: Weighted average outstanding shares — basic 44.6 43.9 Effect of dilutive securities (1) : Stock options, restricted stock units, and employee stock purchase plan 1.8 0.2 Weighted average shares — diluted (2) 46.4 44.1 Net income per common share: Basic $ 0.63 $ 3.14 Diluted $ 0.61 $ 3.12 Stock options and restricted stock units excluded from calculation (2) 0.2 7.6 (1) Calculated using the treasury stock method. (2) The common shares underlying certain stock options and restricted stock units have been excluded from the computation of diluted earnings per share because their impact would be anti-dilutive for the three-month periods ended March 31, 2021 and March 31, 2020.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Our effective income tax rate ( ETR ) for the three months ended March 31, 2021 and 2020 was 13 percent and 20 percent, respectively. Our ETR for the three months ended March 31, 2021 decreased compared to the ETR for the three months ended March 31, 2020 primarily due to excess tax benefits from share-based compensation recognized as a discrete item relative to the amount of pretax income, and a decrease in valuation allowance, partially offset by an increase in state tax expense. We record interest and penalties related to uncertain tax positions as a component of income tax expense. As of March 31, 2021 and December 31, 2020, our total liability for unrecognized tax benefits, including related interest, was approximately $5.0 million and $4.9 million, respectively. The total amount of unrecognized tax benefits relating to our tax positions is subject to change based on future events and it is reasonably possible that the balance could change significantly over the next 12 months. Given the uncertainty of future events, we are unable to reasonably estimate the range of possible adjustments to the balance of our unrecognized tax benefits.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Segment Information	Segment Information We 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): Three Months Ended March 31, 2021 Remodulin (1) Tyvaso (1) Orenitram Unituxin Adcirca Total Net product sales $ 130.2 $ 123.0 $ 72.4 $ 43.9 $ 9.6 $ 379.1 Cost of product sales 8.2 3.1 4.1 3.6 4.0 23.0 Gross profit $ 122.0 $ 119.9 $ 68.3 $ 40.3 $ 5.6 $ 356.1 2020 Net product sales $ 145.3 $ 102.9 $ 69.0 $ 26.6 $ 12.5 $ 356.3 Cost of product sales 6.0 5.1 4.7 2.3 5.3 23.4 Gross profit $ 139.3 $ 97.8 $ 64.3 $ 24.3 $ 7.2 $ 332.9 (1) Net product sales and cost of product sales include sales of delivery devices for the respective product, including, with respect to Remodulin, the Remunity Pump. 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): Three Months Ended March 31, 2021 2020 United States $ 354.3 $ 326.7 Rest-of-World 24.8 29.6 Total $ 379.1 $ 356.3 We recorded revenue from three distributors in the United States that exceeded 10 percent of total revenues. Revenue from these three distributors as a percentage of total revenues is as follows: Three Months Ended March 31, 2021 2020 Distributor 1 54 % 55 % Distributor 2 26 % 25 % Distributor 3 11 % 7 %

Litigation

Litigation	3 Months Ended
	Mar. 31, 2021
Litigation
Litigation	Litigation Sandoz Antitrust Litigation On April 16, 2019, Sandoz Inc. ( Sandoz ) and its marketing partner RareGen, LLC (now known as Liquidia PAH, LLC, a subsidiary of Liquidia Corporation) ( RareGen ), 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 ® 3 cartridges specifically for the delivery of subcutaneous Remodulin, without making these cartridges available for the delivery of Sandoz’s generic version of Remodulin. The parties completed expedited discovery in anticipation of a motion filed by the plaintiffs on October 4, 2019, seeking preliminary injunctive relief. We and Smiths Medical filed a motion to dismiss the complaint, and we filed our opposition to plaintiffs’ motion for a preliminary injunction on October 25, 2019. On January 29, 2020, the Court issued a decision denying the request for preliminary injunction sought by Sandoz and RareGen. According to the Court, “[Sandoz and RareGen] have not met their burden of demonstrating a reasonable probability of eventual success in the litigation.” The Court also denied our and Smiths Medical’s motion to dismiss the entire action. Plaintiffs declined to appeal the Court’s denial of their motion for preliminary injunction. On March 30, 2020, the plaintiffs filed an amended complaint to add a count alleging that we breached our earlier patent settlement agreement with Sandoz by refusing to grant Sandoz access to cartridges. The parties have completed fact discovery and are currently engaging in expert discovery, and we do not anticipate a trial before mid-2022 at the earliest. Smiths Medical was dismissed from the case on November 13, 2020, based on a settlement resolving the disputes between the plaintiffs and Smiths Medical. As part of this settlement, Smiths Medical paid the plaintiffs $4.25 million, disclosed and made available to the plaintiffs certain specifications and other information related to the MS-3 cartridges, and granted to the plaintiffs a non-exclusive, royalty-free license in the United States to Smiths Medical’s patents and copyrights associated with the MS-3 cartridges and certain other information related to the MS-3 pumps and cartridges. We believe plaintiffs’ claims to be meritless and intend to vigorously defend the litigation. However, due to the uncertainty inherent in any litigation, we cannot guarantee that an adverse outcome will not result. Any litigation of this nature could involve substantial cost, and an adverse outcome could result in substantial monetary damages and/or injunctive relief adverse to our business. We currently are not able to reasonably estimate a range of potential losses due to the early stage of the litigation. Patent Litigation with Liquidia Technologies, Inc. On March 30, 2020, Liquidia Technologies, Inc. ( Liquidia ) filed two petitions for inter partes review ( IPR ) with the Patent Trial and Appeal Board ( PTAB ) of the U.S. Patent and Trademark Office ( USPTO ). In its petitions, Liquidia seeks to invalidate U.S. Patent Nos. 9,604,901 (the ’901 patent ) and 9,593,066 (the ’066 patent ), both of which relate to a method of making treprostinil, the active pharmaceutical ingredient in our Remodulin, Tyvaso, and Orenitram products. These patents were issued in March 2017 and are listed in the FDA’s Approved Drug Products with Therapeutic Equivalence Evaluations publication, also known as the Orange Book, for Remodulin, Tyvaso, and Orenitram. In July 2020, we filed preliminary responses to the petitions. On October 13, 2020, the PTAB declined to institute IPR proceedings on the ’066 patent because Liquidia failed to establish a reasonable likelihood of prevailing on any claim relating to the ’066 patent. Also on October 13, 2020, the PTAB instituted IPR proceedings on the ’901 patent, finding that Liquidia had established a reasonable likelihood of prevailing on some of the claims of the ’901 patent. We expect the PTAB will issue a final written decision regarding the ’901 patent IPR around October 2021. Any appeals of the PTAB’s final written decision would delay any final outcome. In January 2020, Liquidia submitted an NDA to the FDA for approval of LIQ861, a dry powder inhalation formulation of treprostinil. This NDA was submitted under the 505(b)(2) regulatory pathway with Tyvaso as the reference listed drug. On April 8, 2020, Liquidia announced that the FDA had accepted its NDA and set a Prescription Drug User Fee Act ( PDUFA ) target action date of November 24, 2020. On November 25, 2020, Liquidia issued a press release stating that the FDA issued a complete response letter for its NDA identifying “the need for additional information and clarification on chemistry, manufacturing and controls (CMC) data pertaining to the drug product and device biocompatibility.” According to Liquidia, it does not anticipate the complete response letter will affect its projected launch timing of LIQ861 in the second half of 2022. In April 2020, we received a Paragraph IV Certification Notice Letter ( Notice Letter ) from Liquidia, stating that it intends to market LIQ861 before the expiration of all patents listed in the Orange Book for Tyvaso. The Notice Letter states that Liquidia’s NDA for LIQ861 contains a Paragraph IV certification alleging that these patents are not valid, not enforceable, and/or will not be infringed by the commercial manufacture, use or sale of LIQ861. On June 4, 2020, we filed a lawsuit in the U.S. District Court for the District of Delaware against Liquidia for infringement of the ’901 patent and the ’066 patent, both of which expire in December 2028. We filed our lawsuit within 45 days of receipt of notice from Liquidia of its NDA filing. As a result, under the Hatch-Waxman Act, the FDA is precluded by regulation from approving Liquidia’s NDA for up to 30 months or until the resolution of the litigation, whichever occurs first. On July 16, 2020, Liquidia filed an answer to our complaint that included counterclaims alleging, among other things, that the patents at issue in the litigation are not valid and will not be infringed by the commercial manufacture, use or sale of LIQ861. On July 21, 2020, the USPTO issued a new patent to us related to Tyvaso. The new patent, U.S. Patent No. 10,716,793 (the ’793 patent ), expires May 14, 2027, and is listed in the Orange Book for Tyvaso. On July 22, 2020, we filed an amended complaint against Liquidia to include a claim for infringement of the ’793 patent. The ’793 patent relates to a method of administering treprostinil via inhalation and includes claims covering the dosing regimen used to administer Tyvaso. On August 5, 2020, Liquidia filed an answer to our amended complaint that repeated its defenses and counterclaims and added new defenses and counterclaims related to the ’793 patent. On August 26, 2020, we filed a motion to dismiss Liquidia’s invalidity defenses with respect to the ’793 patent based on assignor estoppel. The court denied our motion, finding that it is too early in the case to conclusively resolve the issue given the fact-intensive inquiry that is necessary. We can continue to assert an assignor estoppel defense and raise it for resolution later in the case, whether at trial or in a dispositive pre-trial motion. The court set a schedule for the case, including a trial commencing on March 28, 2022. On January 7, 2021, Liquidia filed another petition for IPR with the PTAB. In its petition, Liquidia seeks to invalidate the ’793 patent. We have until May 17, 2021 to file a preliminary response to the petition. The PTAB has three months from receipt of our preliminary response to decide whether to institute the IPR. If the PTAB institutes review, we expect that the PTAB will issue a final written decision regarding the ’793 patent around July 2022. Any appeals of the PTAB’s final written decision would delay any final outcome. We plan to vigorously enforce our intellectual property rights related to Tyvaso. MSP Recovery Litigation On July 27, 2020, MSP Recovery Claims, Series LLC; MSPA Claims 1, LLC; and Series PMPI, a designated series of MAO-MSO Recovery II, LLC ( Plaintiffs ) filed a “Class Action Complaint” (the Complaint ) against Caring Voices Coalition, Inc. ( CVC ) and us in the U.S. District Court for the District of Massachusetts. The Complaint alleges that we violated the federal Racketeer Influenced and Corrupt Organizations act and various state laws by coordinating with CVC when making donations to a pulmonary arterial hypertension fund so that those donations would go towards copayment obligations for Medicare patients taking drugs manufactured and marketed by us. Plaintiffs claim to have received assignments from various Medicare Advantage health plans and other insurance entities that allow them to bring this lawsuit on behalf of those entities to recover allegedly inflated amounts they paid for our drugs. On April 6, 2021, the Court granted our motion to transfer the case to the U.S. District Court for the Southern District of Florida. Two members of the putative class, Humana Inc. and UnitedHealthcare Insurance Company, have informed us that they may bring claims directly against us to recover alleged overpayments. We intend to vigorously defend against this lawsuit. Patent Litigation with ANI Pharmaceuticals, Inc. In February 2021, we received a Paragraph IV certification notice letter from ANI Pharmaceuticals, Inc. ( ANI ) indicating that ANI has submitted an ANDA to the FDA to market a generic version of Orenitram before the expiration of the following patents: U.S. Patent No. Expiration Date 8,252,839 May 2024 9,050,311 May 2024 9,278,901 May 2024 7,544,713 July 2024 7,417,070 July 2026 8,497,393 December 2028 9,604,901 December 2028 9,592,066 December 2028 8,747,897 October 2029 8,410,169 February 2030 8,349,892 January 2031 ANI’s notice letter states that the ANDA contains a Paragraph IV certification alleging that these patents are not valid, not enforceable, and/or will not be infringed by the commercial manufacture, use or sale of the proposed product described in ANI’s ANDA submission. We responded to the ANI notice letter by filing a lawsuit against ANI on April 1, 2021 in the U.S. District Court for the District of Delaware alleging infringement of each of the patents noted above. Under the Hatch-Waxman Act, the FDA is automatically precluded from approving ANI’s ANDA for up to 30 months from receipt of ANI’s notice letter or until the entry by a U.S. District Court of a final judgment that is adverse to us on all patents that form the basis of the stay, whichever occurs first. We previously settled litigation with Actavis Laboratories FL, Inc. ( Actavis ) related to its ANDA submitted to the FDA to market a generic version of Orenitram. Under our settlement agreement, Actavis is permitted to market its generic version of Orenitram in June 2027. If ANI is successful in the pending litigation, it could potentially accelerate Actavis’ launch date. We do not know whether Actavis obtained and, if so, retained, 180 days of exclusivity from other generic competition based on its first-to-file status.

Priority Review Voucher

Priority Review Voucher	3 Months Ended
	Mar. 31, 2021
Research and Development [Abstract]
Arena License Agreement	Priority Review Voucher On December 28, 2020, we entered into an agreement to acquire a rare pediatric disease priority review voucher for $105.0 million. The closing of the transaction was subject to customary closing conditions, including obtaining expiration or early termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvement Act of 1976. On January 21, 2021, we closed the transaction and expensed the $105.0 million within research and development

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recently Issued Accounting Standards	Recently Issued Accounting Standards Accounting Standards Adopted During the Period In December 2019, the Financial Accounting Standards Board ( FASB ) issued Accounting Standards Update ( ASU ) No. 2019-12, Simplifying the Accounting for Income Taxes ( ASU 2019-12 ) , which simplifies the accounting for income taxes by removing certain exceptions to the general principles of Topic 740, Income Taxes, and also improves consistency of application by clarifying and amending existing guidance. ASU 2019-12 is effective for fiscal years beginning after December 15, 2020. We adopted the new standard on January 1, 2021, with no material impact on our financial statements. In January 2020, the FASB issued ASU No. 2020-01, Investments-Equity Securities (Topic 321), Investments-Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815)-Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 (a consensus of the Emerging Issues Task Force) ( ASU 2020-01 ), which addresses the accounting for the transition into and out of the equity method and measuring certain purchased options and forward contracts to acquire investments. ASU 2020-01 is effective for fiscal years beginning after December 15, 2020. We adopted the new standard on January 1, 2021, with no material impact on our financial statements. Accounting Standards Not Yet Adopted In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting ( ASU 2020-04 ), which provides optional expedients and exceptions to lessen the burden of accounting for contract modifications and hedging relationships that reference LIBOR or other reference rates that could be discontinued due to reference rate reform. ASU 2020-04 became effective immediately and may be applied through December 31, 2022. We are currently evaluating the impact of the expedients and exceptions of this new standard on our accounting for our credit agreement, which references LIBOR.

Investments (Tables)

Investments (Tables) - Available-for-Sale Debt Securities	3 Months Ended
	Mar. 31, 2021
Investments
Schedule of 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): As of March 31, 2021 Amortized Gross Gross Fair U.S. government and agency securities $ 1,911.5 $ 7.5 $ (0.4) $ 1,918.6 Corporate debt securities 345.6 2.1 (0.1) 347.6 Total $ 2,257.1 $ 9.6 $ (0.5) $ 2,266.2 Reported under the following captions on our consolidated balance sheets: Current marketable investments $ 832.7 Non-current marketable investments 1,433.5 Total $ 2,266.2 As of December 31, 2020 Amortized Gross Gross Fair U.S. government and agency securities $ 1,902.4 $ 9.8 $ (0.1) $ 1,912.1 Corporate debt securities 331.2 3.2 — 334.4 Total $ 2,233.6 $ 13.0 $ (0.1) $ 2,246.5 Reported under the following captions on our consolidated balance sheets: Cash and cash equivalents $ 79.0 Current marketable investments 1,017.9 Non-current marketable investments 1,149.6 Total $ 2,246.5
Summary of the contractual maturities	The following table summarizes the contractual maturities of available-for-sale debt securities (in millions). Actual maturities may differ from contractual maturities because the issuers of certain of these debt securities have the right to call the securities or prepay their obligations under the securities with or without penalties. As of March 31, 2021 Amortized Cost Fair Value Due within one year $ 829.1 $ 832.7 Due in one to three years 1,428.0 1,433.5 Total $ 2,257.1 $ 2,266.2

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
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 March 31, 2021 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 390.2 $ — $ — $ 390.2 Time deposits (2) 88.0 — — 88.0 U.S. government and agency securities (3) — 1,918.6 — 1,918.6 Corporate debt securities (3) — 347.6 — 347.6 Equity securities (4) 66.3 — — 66.3 Contingent consideration (5) — — 6.0 6.0 Total assets $ 544.5 $ 2,266.2 $ 6.0 $ 2,816.7 Liabilities Contingent consideration (6) — — 15.1 15.1 Total liabilities $ — $ — $ 15.1 $ 15.1 As of December 31, 2020 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ 323.1 $ — $ — $ 323.1 U.S. government and agency securities (3) — 1,912.1 — 1,912.1 Corporate debt securities (3) — 334.4 — 334.4 Equity securities (4) 78.4 — — 78.4 Contingent consideration (5) — — 4.1 4.1 Total assets $ 401.5 $ 2,246.5 $ 4.1 $ 2,652.1 Liabilities Contingent consideration (6) — — 17.1 17.1 Total liabilities $ — $ — $ 17.1 $ 17.1 (1) Included in cash and cash equivalents on our consolidated balance sheets. (2) Included in cash and cash equivalents 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 3— 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 three months ended March 31, 2021 and March 31, 2020, we recognized $96.8 million of net unrealized and realized gains and $6.1 million of net unrealized and realized losses, respectively, on these securities. We recorded these gains and losses on our consolidated statements of operations within other income, net . Refer to Note 3— Investments—Marketable Investments—Investments in Equity Securities with Readily Determinable Fair Values . (5) Included in other current and other non-current assets on our consolidated balance sheets. We estimated the fair value of contingent consideration using a Monte Carlo simulation. The Monte Carlo simulation incorporates Level 3 inputs including price volatility of peer company stocks and the probability of completing certain milestones during a specified period of time. The fair value of our contingent consideration assets increased by $1.9 million from December 31, 2020 to March 31, 2021. The gain was recorded within other income, net on our consolidated statements of operations. (6) Included in non-current liabilities on our consolidated balance sheets. The fair value of our contingent consideration obligations 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 our contingent consideration obligations for the three months ended March 31, 2021 was the result of our decision in January 2021 to discontinue our research and development efforts related to biomechanical lungs. As a result of the decision, we de-recognized $2.0 million of a related contingent consideration liability during the first quarter of 2021. The gain was recorded within research and development on our consolidated statements of operations.

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
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): March 31, 2021 December 31, 2020 Raw materials $ 16.0 $ 18.4 Work-in-progress 31.2 29.5 Finished goods 45.0 38.6 Total inventories $ 92.2 $ 86.5

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of goodwill and other intangible assets	Goodwill and other intangible assets comprise the following (in millions): As of March 31, 2021 As of December 31, 2020 Gross Accumulated Net Gross Accumulated Net Goodwill $ 28.0 $ — $ 28.0 $ 28.0 $ — $ 28.0 Other intangible assets: Technology, patents, and trade names 6.7 (5.5) 1.2 6.7 (5.5) 1.2 In-process research and development (1) (2) 15.5 — 15.5 128.9 — 128.9 Total $ 50.2 $ (5.5) $ 44.7 $ 163.6 $ (5.5) $ 158.1 (1) In March 2021, we decided to discontinue the U.S. development of Trevyent ® , due to written comments provided by the FDA in February 2021. The FDA provided these written comments following a meeting between us and the FDA to discuss our planned resubmission of the New Drug Application for Trevyent in light of a Complete Response Letter issued by the FDA in April 2020. We determined this to be a potential indicator of impairment of our in-process research and development ( IPR&D ) asset related to Trevyent, which had a carrying value of $107.3 million as of December 31, 2020. Based on our decision to discontinue the U.S. development of Trevyent, we fully impaired the IPR&D asset related to Trevyent during the first quarter of 2021. The $107.3 million impairment charge was recorded within research and development on our consolidated statements of operations. (2) In January 2021, we decided to discontinue our research and development efforts related to biomechanical lungs. As a result of the decision, we fully impaired the IPR&D asset related to these efforts, which had a carrying value of $6.1 million, during the first quarter of 2021. The impairment charge was recorded within research and development on our consolidated statements of operations.

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant, and equipment ( PP&E ) consists of the following (in millions): March 31, 2021 December 31, 2020 Land and land improvements $ 75.0 $ 74.9 Buildings, building improvements, and leasehold improvements 601.7 593.6 Buildings under construction 45.6 47.4 Furniture, equipment, and vehicles 308.6 325.0 Subtotal 1,030.9 1,040.9 Less—accumulated depreciation (317.2) (309.3) Property, plant, and equipment, net $ 713.7 $ 731.6

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Share-Based Compensation
Schedule of components of share-based compensation expense recognized	The following table reflects the components of share-based compensation expense recognized in our consolidated statements of operations (in millions): Three Months Ended 2021 2020 Stock options $ 8.3 $ 16.4 Restricted stock units 5.7 4.0 STAP awards 25.7 10.1 Employee stock purchase plan 0.4 0.3 Total share-based compensation expense before tax $ 40.1 $ 30.8
Stock options
Share-Based Compensation
Summary of weighted-average assumptions to measure the fair value of stock options	The following weighted average assumptions were used in estimating the fair value of stock options granted to employees during the three months ended March 31, 2021 and 2020: March 31, 2021 March 31, 2020 Expected term of awards (in years) 6.0 6.0 Expected volatility 32.7 % 32.4 % Risk-free interest rate 1.1 % 0.8 % Expected dividend yield — % — %
Schedule of activity and status of stock options	A summary of the activity and status of stock options under our equity incentive plans during the three-month period ended March 31, 2021 is presented below: Number of Weighted Weighted Aggregate Outstanding at January 1, 2021 7,680,194 $ 126.27 Granted 14,603 164.10 Exercised (132,789) 131.83 Forfeited/canceled (213) 146.03 Outstanding at March 31, 2021 7,561,795 $ 126.24 5.4 $ 311.5 Exercisable at March 31, 2021 5,801,938 $ 125.75 5.1 $ 242.2 Unvested at March 31, 2021 1,759,857 $ 127.88 6.1 $ 69.3
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense related to stock options is recorded as follows (in millions): Three Months Ended 2021 2020 Cost of product sales $ 0.1 $ 0.2 Research and development 0.2 0.9 Selling, general, and administrative 8.0 15.3 Share-based compensation expense before taxes 8.3 16.4 Related income tax benefit (0.3) (3.7) Share-based compensation expense, net of taxes $ 8.0 $ 12.7
Summary of stock option exercise data	Stock option exercise data is summarized below (dollars in millions): Three Months Ended 2021 2020 Number of options exercised 132,789 13,500 Cash received $ 17.5 $ 0.7 Total intrinsic value of options exercised $ 4.7 $ 0.6
Restricted stock units
Share-Based Compensation
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense related to restricted stock units is recorded as follows (in millions): Three Months Ended 2021 2020 Cost of product sales $ 0.5 $ 0.3 Research and development 1.8 1.4 Selling, general, and administrative 3.4 2.3 Share-based compensation expense before taxes 5.7 4.0 Related income tax benefit (1.3) (0.9) Share-based compensation expense, net of taxes $ 4.4 $ 3.1
Schedule of restricted stock units activity	A summary of the activity with respect to, and status of, restricted stock units during the three-month period ended March 31, 2021 is presented below: Number of Weighted Unvested at January 1, 2021 440,528 $ 102.40 Granted 171,244 164.16 Vested (181,297) 104.68 Forfeited/canceled (6,311) 116.70 Unvested at March 31, 2021 424,164 $ 126.15
STAP awards
Share-Based Compensation
Schedule of share-based compensation expense (benefit) recognized	Share-based compensation expense recognized in connection with STAP awards is as follows (in millions): Three Months Ended 2021 2020 Cost of product sales $ 1.1 $ 0.7 Research and development 4.3 2.2 Selling, general, and administrative 20.3 7.2 Share-based compensation expense before taxes 25.7 10.1 Related income tax benefit (4.9) (2.3) Share-based compensation expense, net of taxes $ 20.8 $ 7.8
Schedule of weighted-average assumptions to measure the fair value of outstanding STAP awards	The table below includes the weighted average assumptions used to measure the fair value of the outstanding STAP awards: March 31, 2021 March 31, 2020 Expected term of awards (in years) 1.6 2.0 Expected volatility 33.3 % 32.5 % Risk-free interest rate 0.2 % 0.2 % Expected dividend yield — % — %
Summary of the activity and status of STAP awards	A summary of the activity and status of STAP awards during the three-month period ended March 31, 2021 is presented below: Number of Weighted Weighted Aggregate Outstanding at January 1, 2021 2,121,860 $ 118.48 Granted — — Exercised (194,933) 90.06 Forfeited/canceled (562) 145.30 Outstanding at March 31, 2021 1,926,365 $ 121.35 3.2 $ 88.6 Exercisable at March 31, 2021 1,916,365 $ 121.71 3.2 $ 87.4 Unvested at March 31, 2021 10,000 $ 52.57 1.7 $ 1.2

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Common Share
Schedule of components of basic and diluted earnings (loss) per common share	The components of basic and diluted earnings per common share comprised the following (in millions, except per share amounts): Three Months Ended 2021 2020 Numerator: Net income $ 28.3 $ 137.7 Denominator: Weighted average outstanding shares — basic 44.6 43.9 Effect of dilutive securities (1) : Stock options, restricted stock units, and employee stock purchase plan 1.8 0.2 Weighted average shares — diluted (2) 46.4 44.1 Net income per common share: Basic $ 0.63 $ 3.14 Diluted $ 0.61 $ 3.12 Stock options and restricted stock units excluded from calculation (2) 0.2 7.6 (1) Calculated using the treasury stock method. (2) The common shares underlying certain stock options and restricted stock units have been excluded from the computation of diluted earnings per share because their impact would be anti-dilutive for the three-month periods ended March 31, 2021 and March 31, 2020.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Schedule of net product sales, cost of product sales and gross profit for each commercial products	Net product sales, cost of product sales, and gross profit for each of our commercial products were as follows (in millions): Three Months Ended March 31, 2021 Remodulin (1) Tyvaso (1) Orenitram Unituxin Adcirca Total Net product sales $ 130.2 $ 123.0 $ 72.4 $ 43.9 $ 9.6 $ 379.1 Cost of product sales 8.2 3.1 4.1 3.6 4.0 23.0 Gross profit $ 122.0 $ 119.9 $ 68.3 $ 40.3 $ 5.6 $ 356.1 2020 Net product sales $ 145.3 $ 102.9 $ 69.0 $ 26.6 $ 12.5 $ 356.3 Cost of product sales 6.0 5.1 4.7 2.3 5.3 23.4 Gross profit $ 139.3 $ 97.8 $ 64.3 $ 24.3 $ 7.2 $ 332.9 (1) Net product sales and cost of product sales include sales of delivery devices for the respective product, including, with respect to Remodulin, the Remunity Pump.
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): Three Months Ended March 31, 2021 2020 United States $ 354.3 $ 326.7 Rest-of-World 24.8 29.6 Total $ 379.1 $ 356.3
Schedule of revenue from two specialty pharmaceutical distributors in the United States as a percentage of total revenue	We recorded revenue from three distributors in the United States that exceeded 10 percent of total revenues. Revenue from these three distributors as a percentage of total revenues is as follows: Three Months Ended March 31, 2021 2020 Distributor 1 54 % 55 % Distributor 2 26 % 25 % Distributor 3 11 % 7 %

Litigation (Tables)

Litigation (Tables)	3 Months Ended
	Mar. 31, 2021
Litigation
Schedule of patent expiration date	In February 2021, we received a Paragraph IV certification notice letter from ANI Pharmaceuticals, Inc. ( ANI ) indicating that ANI has submitted an ANDA to the FDA to market a generic version of Orenitram before the expiration of the following patents: U.S. Patent No. Expiration Date 8,252,839 May 2024 9,050,311 May 2024 9,278,901 May 2024 7,544,713 July 2024 7,417,070 July 2026 8,497,393 December 2028 9,604,901 December 2028 9,592,066 December 2028 8,747,897 October 2029 8,410,169 February 2030 8,349,892 January 2031

Investments - Available-for-Sal

Investments - Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	$ 2,257.1	$ 2,233.6
Gross Unrealized Gains	9.6	13
Gross Unrealized Losses	(0.5)	(0.1)
Fair Value	2,266.2	2,246.5
U.S. government and agency securities
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	1,911.5	1,902.4
Gross Unrealized Gains	7.5	9.8
Gross Unrealized Losses	(0.4)	(0.1)
Fair Value	1,918.6	1,912.1
Corporate debt securities
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	345.6	331.2
Gross Unrealized Gains	2.1	3.2
Gross Unrealized Losses	(0.1)	0
Fair Value	$ 347.6	$ 334.4

Investments - Current and Non-c

Investments - Current and Non-current of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Reported under the following captions on our consolidated balance sheet:
Total	$ 2,266.2	$ 2,246.5
Cash and cash equivalents
Reported under the following captions on our consolidated balance sheet:
Total		79
Current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	832.7	1,017.9
Non-current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	$ 1,433.5	$ 1,149.6

Investments - Contractual Matur

Investments - Contractual Maturities of Available-for-Sale Marketable Investments (Details) $ in Millions	Mar. 31, 2021USD ($)
Amortized Cost
Due within one year	$ 829.1
Due in one to three years	1,428
Total	2,257.1
Fair Value
Due within one year	832.7
Due in one to three years	1,433.5
Total	$ 2,266.2

Investments - Investments in Eq

Investments - Investments in Equity Securities with Readily Determinable Fair Values (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Investments [Abstract]
Investments in equity securities with readily determinable fair value	$ 66.3		$ 78.4
Sales of investments in equity securities	108.9	$ 13.2
Realized gain	$ 91.9

Investments - Investments in Pr

Investments - Investments in Privately-Held Companies (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)investment	Dec. 31, 2020USD ($)
Investments in Privately-Held Companies and Investments in Equity Securities with Readily Determinable Fair Values
Impairments of investments in privately-held companies	$ 0	$ 5.6
Privately-held Companies
Investments in Privately-Held Companies and Investments in Equity Securities with Readily Determinable Fair Values
Investments in privately-held companies	$ 84.8		$ 84.8
Increase in the value of investment		$ 22.5
Number of impaired investments | investment		2
Impairments of investments in privately-held companies		$ 5.6

Investments - Variable Interest

Investments - Variable Interest Entity (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Assets	$ 4,641	$ 4,615
Accounts payable and accrued expenses	165	187
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	12.3	11.7
Accounts payable and accrued expenses	4.6	$ 24
Maximum exposure to loss	$ 12.3

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Liabilities
Increase in fair value of contingent consideration asset	$ 1.9
Recurring fair value measurements | Equity securities | Other income (expense), net
Liabilities
Net unrealized and realized gains (losses) on securities	96.8	$ (6.1)
Recurring fair value measurements | Level 1
Assets
Total assets	544.5		$ 401.5
Liabilities
Contingent consideration	0		0
Total liabilities	0		0
Recurring fair value measurements | Level 1 | Money market funds
Assets
Total assets	390.2		323.1
Recurring fair value measurements | Level 1 | Time deposits
Assets
Total assets	88
Recurring fair value measurements | Level 1 | U.S. government and agency securities
Assets
Total assets	0		0
Recurring fair value measurements | Level 1 | Corporate debt securities
Assets
Total assets	0		0
Recurring fair value measurements | Level 1 | Equity securities
Assets
Total assets	66.3		78.4
Recurring fair value measurements | Level 1 | Contingent consideration
Assets
Total assets	0		0
Recurring fair value measurements | Level 2
Assets
Total assets	2,266.2		2,246.5
Liabilities
Contingent consideration	0		0
Total liabilities	0		0
Recurring fair value measurements | Level 2 | Money market funds
Assets
Total assets	0		0
Recurring fair value measurements | Level 2 | Time deposits
Assets
Total assets	0
Recurring fair value measurements | Level 2 | U.S. government and agency securities
Assets
Total assets	1,918.6		1,912.1
Recurring fair value measurements | Level 2 | Corporate debt securities
Assets
Total assets	347.6		334.4
Recurring fair value measurements | Level 2 | Equity securities
Assets
Total assets	0		0
Recurring fair value measurements | Level 2 | Contingent consideration
Assets
Total assets	0		0
Recurring fair value measurements | Level 3
Assets
Total assets	6		4.1
Liabilities
Contingent consideration	15.1		17.1
Total liabilities	15.1		17.1
Recurring fair value measurements | Level 3 | Money market funds
Assets
Total assets	0		0
Recurring fair value measurements | Level 3 | Time deposits
Assets
Total assets	0
Recurring fair value measurements | Level 3 | U.S. government and agency securities
Assets
Total assets	0		0
Recurring fair value measurements | Level 3 | Corporate debt securities
Assets
Total assets	0		0
Recurring fair value measurements | Level 3 | Equity securities
Assets
Total assets	0		0
Recurring fair value measurements | Level 3 | Contingent consideration
Assets
Total assets	6		4.1
Liabilities
Contingent consideration	(2)
Recurring fair value measurements | Balance
Assets
Total assets	2,816.7		2,652.1
Liabilities
Contingent consideration	15.1		17.1
Total liabilities	15.1		17.1
Recurring fair value measurements | Balance | Money market funds
Assets
Total assets	390.2		323.1
Recurring fair value measurements | Balance | Time deposits
Assets
Total assets	88
Recurring fair value measurements | Balance | U.S. government and agency securities
Assets
Total assets	1,918.6		1,912.1
Recurring fair value measurements | Balance | Corporate debt securities
Assets
Total assets	347.6		334.4
Recurring fair value measurements | Balance | Equity securities
Assets
Total assets	66.3		78.4
Recurring fair value measurements | Balance | Contingent consideration
Assets
Total assets	$ 6		$ 4.1

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Inventories
Raw materials	$ 16	$ 18.4
Work-in-progress	31.2	29.5
Finished goods	45	38.6
Total inventories	$ 92.2	$ 86.5

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Goodwill and Other Intangible Assets
Goodwill, gross	$ 28		$ 28
Goodwill, net	28		28
Finite-Lived Intangible Assets, Net
Other intangible assets, accumulated amortization	(5.5)		(5.5)
Intangible Assets, Net (Including Goodwill)
Total goodwill and other intangible assets, gross	50.2		163.6
Total goodwill and other intangible assets, net	44.7		158.1
Research and development	303.7	$ 73.2
Technology, patents, and trade names
Finite-Lived Intangible Assets, Net
Other intangible assets, gross	6.7		6.7
Other intangible assets, accumulated amortization	(5.5)		(5.5)
Other intangible assets, net	1.2		1.2
In-process research and development
Finite-Lived Intangible Assets, Net
Other intangible assets, gross	15.5		128.9
Other intangible assets, net	15.5		128.9
Intangible Assets, Net (Including Goodwill)
Carrying value of Trevyent intangible asset			$ 107.3
In Process Research and Development, Trevyent
Intangible Assets, Net (Including Goodwill)
Research and development	107.3
In Process Research and Development, Biomechanical Lungs
Intangible Assets, Net (Including Goodwill)
Research and development	$ 6.1

Property, Plant, and Equipmen_2

Property, Plant, and Equipment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,030.9	$ 1,040.9
Less—accumulated depreciation	(317.2)	(309.3)
Property, plant, and equipment, net	713.7	731.6
Impairments of property, plant, and equipment	17
Research and development
Property, Plant and Equipment [Line Items]
Impairments of property, plant, and equipment	15.5
Selling, general, and administrative
Property, Plant and Equipment [Line Items]
Impairments of property, plant, and equipment	1.5
Land and land improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	75	74.9
Buildings, building improvements, and leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	601.7	593.6
Buildings under construction
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	45.6	47.4
Furniture, equipment, and vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	308.6	$ 325
Facility
Property, Plant and Equipment [Line Items]
Impairments of property, plant, and equipment	$ 11.6

Debt (Details)

Debt (Details) - USD ($)	1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2020	Jun. 30, 2018	Mar. 31, 2021	Dec. 31, 2020
Credit Agreement
Debt
Debt, maturity term	1 year
Outstanding aggregate principal balance	$ 800,000,000		$ 800,000,000	$ 800,000,000
Repayment term			1 year	1 year
First unsecured revolving credit facility
Debt
Borrowing		$ 1,000,000,000
Second unsecured revolving credit facility
Debt
Borrowing		500,000,000
Increase in borrowing capacity		$ 300,000,000
2018 Credit Agreement | Other current assets
Debt
Debt issuance costs capitalized			$ 2,400,000
2018 Credit Agreement | Other non-current assets
Debt
Debt issuance costs capitalized			$ 8,700,000

Share-Based Compensation - Gene

Share-Based Compensation - General (Details)	1 Months Ended	3 Months Ended
	Feb. 28, 2019shares	Mar. 31, 2021planshares
Share-Based Compensation
Number of equity incentive plans | plan		2
2015 Plan
Share-Based Compensation
Maximum number of shares authorized to be issued		10,000,000
2019 Inducement Plan | Newly-hired employees
Share-Based Compensation
Number of equity incentive plans | plan		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 by Plan (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-Based Compensation
Total share-based compensation expense before tax	$ 40.1	$ 30.8
Stock options
Share-Based Compensation
Total share-based compensation expense before tax	8.3	16.4
Restricted stock units
Share-Based Compensation
Total share-based compensation expense before tax	5.7	4
STAP awards
Share-Based Compensation
Total share-based compensation expense before tax	25.7	10.1
Employee stock purchase plan
Share-Based Compensation
Total share-based compensation expense before tax	$ 0.4	$ 0.3

Share-Based Compensation - Assu

Share-Based Compensation - Assumptions For Stock Options (Details) - Stock options	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Method and assumptions on valuation of stock options
Expected term of awards (in years)	6 years	6 years
Expected volatility	32.70%	32.40%
Risk-free interest rate	1.10%	0.80%
Expected dividend yield	0.00%	0.00%

Share-Based Compensation - Stoc

Share-Based Compensation - Stock and Status (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Number of Options
Outstanding at beginning of the period (in shares)	7,680,194
Granted (in shares)	14,603
Exercised (in shares)	(132,789)	(13,500)
Forfeited/canceled (in shares)	(213)
Outstanding at the end of the period (in shares)	7,561,795
Exercisable at the end of the period (in shares)	5,801,938
Unvested at the end of the period (in shares)	1,759,857
Weighted Average Exercise Price
Outstanding at beginning of the period (in dollars per share)	$ 126.27
Granted (in dollars per share)	164.10
Exercised (in dollars per share)	131.83
Forfeited (in dollars per share)	146.03
Outstanding at the end of the period (in dollars per share)	126.24
Exercisable at the end of the period (in dollars per share)	125.75
Unvested at the end of the period (in dollars per share)	$ 127.88
Weighted Average Remaining Contractual Term (in Years)
Outstanding at the end of the period (in Years)	5 years 4 months 24 days
Exercisable at the end of the period (in Years)	5 years 1 month 6 days
Unvested at the end of the period (in Years)	6 years 1 month 6 days
Aggregate Intrinsic Value (in millions)
Outstanding at the end of the period	$ 311.5
Exercisable at the end of the period	242.2
Unvested at the end of the period	$ 69.3
Weighted average grant date fair value of stock options (in dollars per share)	$ 54.63	$ 29.85
Aggregate grant date fair value	$ 0.8	$ 0.5
Total grant date fair value of employee stock options that vested	$ 48.1	$ 69.8

Share-Based Compensation - Shar

Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based compensation expense
Share-based compensation expense before taxes	$ 40.1	$ 30.8
Unrecognized compensation cost	41.1
Stock options
Share-based compensation expense
Share-based compensation expense before taxes	8.3	16.4
Related income tax benefit	(0.3)	(3.7)
Share-based compensation expense, net of taxes	$ 8	12.7
Weighted average remaining vesting period	1 year 10 months 24 days
Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	$ 5.7	4
Related income tax benefit	(1.3)	(0.9)
Share-based compensation expense, net of taxes	$ 4.4	3.1
Weighted average remaining vesting period	2 years 4 months 24 days
Unrecognized compensation cost	$ 50
Cost of product sales | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	0.1	0.2
Cost of product sales | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	0.5	0.3
Research and development | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	0.2	0.9
Research and development | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	1.8	1.4
Selling, general, and administrative | Stock options
Share-based compensation expense
Share-based compensation expense before taxes	8	15.3
Selling, general, and administrative | Restricted stock units
Share-based compensation expense
Share-based compensation expense before taxes	$ 3.4	$ 2.3

Share-Based Compensation - St_2

Share-Based Compensation - Stock Options Exercise Data (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Summary of stock option exercise data
Cash received	$ 17.5	$ 0.7
Stock options
Summary of stock option exercise data
Number of options exercised	132,789	13,500
Cash received	$ 17.5	$ 0.7
Total intrinsic value of options exercised	$ 4.7	$ 0.6

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Options Activity and Status (Details) - Restricted stock units	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Share-Based Compensation
Number of shares of common stock entitled to recipient upon vesting	1
Number of Restricted Stock Units
Unvested at beginning of the period (in shares)	440,528
Granted (in shares)	171,244
Vested (in shares)	(181,297)
Forfeited/cancelled (in shares)	(6,311)
Unvested at the end of the period (in shares)	424,164
Weighted Average Grant Date Fair Value
Unvested at beginning of the period (in dollars per share) | $ / shares	$ 102.40
Granted (in dollars per share) | $ / shares	164.16
Vested (in dollars per share) | $ / shares	104.68
Forfeited/cancelled (in dollars per share) | $ / shares	116.70
Unvested at the end of the period (in dollars per share) | $ / shares	$ 126.15

Share-Based Compensation - Bene

Share-Based Compensation - Benefit recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	$ 40.1	$ 30.8
Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	5.7	4
Related income tax benefit	(1.3)	(0.9)
Share-based compensation expense, net of taxes	4.4	3.1
STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	25.7	10.1
Related income tax benefit	(4.9)	(2.3)
Share-based compensation expense, net of taxes	20.8	7.8
Cash payments on awards exercised during the period	15.4	3
Cost of product sales | Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	0.5	0.3
Cost of product sales | STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	1.1	0.7
Research and development | Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	1.8	1.4
Research and development | STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	4.3	2.2
Selling, general, and administrative | Restricted stock units
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	3.4	2.3
Selling, general, and administrative | STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Total share-based compensation expense before tax	$ 20.3	$ 7.2

Share-Based Compensation - STAP

Share-Based Compensation - STAP awards (Details) - STAP awards - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Awards granted
Grant expiration period from the grant date	4 years
Aggregate STAP liability	$ 107.1		$ 96.8
Weighted-average assumptions used to measure the fair value of the outstanding STAP awards:
Expected term of awards (in years)	1 year 7 months 6 days	2 years
Expected volatility	33.30%	32.50%
Risk-free interest rate (as a percent)	0.20%	0.20%
Expected dividend yield	0.00%	0.00%
Closing price of common stock (in dollars per share)	$ 167.27	$ 94.83	$ 151.79
Number of Awards
Outstanding at beginning of period (in shares)	2,121,860
Granted (in shares)	0
Exercised (in shares)	(194,933)
Forfeited/cancelled (in shares)	(562)
Outstanding at end of period (in shares)	1,926,365
Exercisable at end of period (in shares)	1,916,365
Unvested at end of period (in shares)	10,000
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share)	$ 118.48
Granted (in dollars per share)	0
Exercised (in dollars per share)	90.06
Forfeited (in dollars per share)	145.30
Outstanding at end of period (in dollars per share)	121.35
Exercisable at end of period (in dollars per share)	121.71
Unvested at end of period (in dollars per share)	$ 52.57
Weighted Average Remaining Contractual Term (in Years)
Outstanding at end of the period	3 years 2 months 12 days
Exercisable at end of period	3 years 2 months 12 days
Unvested at end of period	1 year 8 months 12 days
Aggregate Intrinsic Value (in millions)
Outstanding at end of period	$ 88.6
Exercisable at end of period	87.4
Unvested at end of period	$ 1.2

Share-Based Compensation - Empl

Share-Based Compensation - Employee Stock Purchase Plan (Details) - Employee stock purchase plan	3 Months Ended
	Mar. 31, 2021shares
Share-based compensation expense
Maximum percentage of compensation employees may contribute for ESPP	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	85.00%
Maximum number of shares each eligible employees may purchase in any given offering period	4,000
Maximum number of shares authorized to be issued	3,000,000

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net income	$ 28.3	$ 137.7
Denominator:
Weighted average outstanding shares — basic	44.6	43.9
Effect of dilutive securities:
Stock options, restricted stock units, and employee stock purchase plan (in shares)	1.8	0.2
Weighted average shares - diluted (in shares)	46.4	44.1
Net income per common share:
Basic (in dollars per share)	$ 0.63	$ 3.14
Diluted (in dollars per share)	$ 0.61	$ 3.12
Stock options and restricted stock units excluded from calculation (in shares)	0.2	7.6

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Effective income tax rate (as a percent)	13.00%	20.00%
Unrecognized tax benefits, including interest and penalties	$ 5		$ 4.9

Segment Information - General (

Segment Information - General (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)segmentdistributor	Mar. 31, 2020USD ($)
Net product sales, cost of product sales and gross profit by product
Number of operating segments | segment	1
Net product sales	$ 379.1	$ 356.3
Cost of product sales	23	23.4
Gross profit	$ 356.1	332.9
Number of distributors | distributor	3
Remodulin
Net product sales, cost of product sales and gross profit by product
Net product sales	$ 130.2	145.3
Cost of product sales	8.2	6
Gross profit	122	139.3
Tyvaso
Net product sales, cost of product sales and gross profit by product
Net product sales	123	102.9
Cost of product sales	3.1	5.1
Gross profit	119.9	97.8
Orenitram
Net product sales, cost of product sales and gross profit by product
Net product sales	72.4	69
Cost of product sales	4.1	4.7
Gross profit	68.3	64.3
Unituxin
Net product sales, cost of product sales and gross profit by product
Net product sales	43.9	26.6
Cost of product sales	3.6	2.3
Gross profit	40.3	24.3
Adcirca
Net product sales, cost of product sales and gross profit by product
Net product sales	9.6	12.5
Cost of product sales	4	5.3
Gross profit	$ 5.6	$ 7.2

Segment Information - Geographi

Segment Information - Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues from external customers by geographic area
Total revenues	$ 379.1	$ 356.3
United States
Revenues from external customers by geographic area
Total revenues	354.3	326.7
Rest-of-World
Revenues from external customers by geographic area
Total revenues	$ 24.8	$ 29.6

Segment Information - Concentra

Segment Information - Concentration Risk (Details) - distributor	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Information
Number of distributors	3
Net revenues | Customer concentration | Distributor 1
Segment Information
Concentration risk, percentage	54.00%	55.00%
Net revenues | Customer concentration | Distributor 2
Segment Information
Concentration risk, percentage	26.00%	25.00%
Net revenues | Customer concentration | Distributor 3
Segment Information
Concentration risk, percentage	11.00%	7.00%

Litigation (Details)

Litigation (Details) $ in Thousands	Apr. 01, 2021	Nov. 13, 2020USD ($)	Jun. 04, 2020	Mar. 30, 2020petition
Sandoz Inc. | Smiths Medical ASD, Inc.
Litigation
Payments for legal settlements | $		$ 4,250
Liquidia Technologies, Inc.
Litigation
Number of petitions | petition				2
Time period to file a preliminary response to the petitions			45 days
Maximum period for which the FDA is automatically precluded from approving ANDA			30 months
ANI Pharmaceuticals, Inc. | Subsequent Event
Litigation
Maximum period for which the FDA is automatically precluded from approving ANDA	30 months

Priority Review Voucher (Detail

Priority Review Voucher (Details) - USD ($) $ in Millions	Jan. 21, 2021	Dec. 28, 2020	Mar. 31, 2021	Mar. 31, 2020
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development			$ 303.7	$ 73.2
Rare Pediatric Disease Priority Review Voucher
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development agreement, value		$ 105
Research and development	$ 105