United Therapeutics (UTHR) 10-Q 29 Apr 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 22, 2020
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
Document Transition Report	false
Entity File Number	0-26301
Entity Registrant Name	United Therapeutics Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	52-1984749
Entity Address, Address Line One	1040 Spring Street
Entity Address, City or Town	Silver Spring
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20910
City Area Code	301
Local Phone Number	608-9292
Security 12b Title	Common Stock
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		44,012,324
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001082554
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 875.2	$ 738.4
Marketable investments	669.3	747.5
Accounts receivable, no allowance for 2020 and 2019	149.6	151.4
Inventories, net	92	93.4
Other current assets	60.2	133.8
Total current assets	1,846.3	1,864.5
Marketable investments	868	767.5
Goodwill and other intangible assets, net	158.3	158.3
Property, plant and equipment, net	739.2	738.5
Deferred tax assets, net	246.1	230
Other non-current assets	168	154.6
Total assets	4,025.9	3,913.4
Current liabilities:
Accounts payable and accrued expenses	130.3	148.4
Line of credit (current)		250
Share tracking awards plan	32	25
Other current liabilities	45	39.6
Total current liabilities	207.3	463
Line of credit (non-current)	800	600
Other non-current liabilities	70.1	70
Total liabilities	1,077.4	1,133
Stockholders' equity:
Common stock, par value $.01, 245,000,000 shares authorized, 70,621,284 and 70,503,775 shares issued, and 44,002,068 and 43,884,559 shares outstanding at March 31, 2020 and December 31, 2019, respectively	0.7	0.7
Additional paid-in capital	2,068.4	2,047.9
Accumulated other comprehensive loss	(3.5)	(14.2)
Treasury stock, 26,619,216 shares at March 31, 2020 and December 31, 2019	(2,579.2)	(2,579.2)
Retained earnings	3,462.1	3,325.2
Total stockholders' equity	2,948.5	2,780.4
Total liabilities and stockholders' equity	4,025.9	3,913.4
Preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued
Series A junior participating preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accounts receivable, allowance (in dollars)	$ 0	$ 0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	245,000,000	245,000,000
Common stock, shares issued	70,621,284	70,503,775
Common stock, shares outstanding	44,002,068	43,884,559
Treasury stock, shares	26,619,216	26,619,216
Preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Series A junior participating preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues:
Total revenues	$ 356.3	$ 362.6
Operating expenses:
Cost of product sales	23.4	29.1
Research and development	73.2	897.4
Selling, general, and administrative	93	92
Total operating expenses	189.6	1,018.5
Operating income (loss)	166.7	(655.9)
Interest income	10	9.8
Interest expense	(8.2)	(10.3)
Other income, net	8.7	5.8
Impairments of investments in privately-held companies	(5.6)
Total other income, net	4.9	5.3
Income (loss) before income taxes	171.6	(650.6)
Income tax (expense) benefit	(33.9)	156
Net income (loss)	$ 137.7	$ (494.6)
Net income (loss) per common share:
Basic (in dollars per share)	$ 3.14	$ (11.32)
Diluted (in dollars per share)	$ 3.12	$ (11.32)
Weighted average number of common shares outstanding:
Basic (in shares)	43.9	43.7
Diluted (in shares)	44.1	43.7
Net product sales
Revenues:
Total revenues	$ 356.3	$ 362.6

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Comprehensive income:
Net income (loss)	$ 137.7	$ (494.6)
Defined benefit pension plan:
Actuarial gain arising during period, net of tax	0.2
Amortization of actuarial gain and prior service cost included in net periodic pension cost, net of tax	0.3	0.1
Total defined benefit pension plan, net of tax	0.5	0.1
Unrealized gains on available-for-sale securities, net of tax	10.2	2.6
Other comprehensive income, net of tax	10.7	2.7
Comprehensive income (loss)	$ 148.4	$ (491.9)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Treasury Stock	Retained Earnings	Total
Balance at Dec. 31, 2018	$ 0.7	$ 1,940.2	$ (7.9)	$ (2,579.2)	$ 3,434.8	$ 2,788.6
Balance (in shares) at Dec. 31, 2018	70.2
Increase (Decrease) in Stockholders' Equity
Net income					(494.6)	(494.6)
Unrealized gains on available-for-sale securities			2.6			2.6
Defined benefit pension plan			0.1			0.1
Shares issued under employee stock purchase plan		2.2				2.2
Restricted stock units withheld for taxes		(1.9)				(1.9)
Exercise of stock options		8.8				8.8
Exercise of stock options (in shares)	0.2
Share-based compensation		18.3				18.3
Cumulative effect of accounting change					(5.1)	(5.1)
Balance at Mar. 31, 2019	$ 0.7	1,967.6	(5.2)	(2,579.2)	2,935.1	2,319
Balance (in shares) at Mar. 31, 2019	70.4
Balance at Dec. 31, 2019	$ 0.7	2,047.9	(14.2)	(2,579.2)	3,325.2	2,780.4
Balance (in shares) at Dec. 31, 2019	70.5
Increase (Decrease) in Stockholders' Equity
Net income					137.7	137.7
Unrealized 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
Common stock issued for RSUs vested (in shares)	0.1
Restricted stock units withheld for taxes		(3.4)				(3.4)
Exercise of stock options		0.7				0.7
Share-based compensation		20.7				20.7
Cumulative effect of accounting change					(0.8)	(0.8)
Balance at Mar. 31, 2020	$ 0.7	$ 2,068.4	$ (3.5)	$ (2,579.2)	$ 3,462.1	$ 2,948.5
Balance (in shares) at Mar. 31, 2020	70.6

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ 137.7	$ (494.6)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	12.4	10.3
Share-based compensation expense	30.8	29.2
Impairments of investments in privately-held companies	5.6
Other	(22.8)	6.7
Changes in operating assets and liabilities:
Accounts receivable	1.7	16
Inventories	6.1	1.7
Accounts payable and accrued expenses	(18.8)	(27.7)
Other assets and liabilities	61.9	(169)
Net cash provided by (used in) operating activities	214.6	(627.4)
Cash flows from investing activities:
Purchases of property, plant and equipment	(13)	(25.1)
Sales/maturities of held-to-maturity investments		37.4
Purchases of available-for-sale investments	(479.2)	(379.5)
Sales/maturities of available-for-sale investments	451.4	313.9
Sales of investments in equity securities	13.2
Purchase of investments in privately-held companies		(7)
Net cash used in investing activities	(27.6)	(60.3)
Cash flows from financing activities:
Proceeds from line of credit		800
Repayment of line of credit	(50)
Proceeds from the exercise of stock options	0.7	8.8
Proceeds from the issuance of stock under employee stock purchase plan	2.5	2.2
Restricted stock units withheld for taxes	(3.4)	(1.9)
Net cash (used in) provided by financing activities	(50.2)	809.1
Net increase in cash and cash equivalents	136.8	121.4
Cash and cash equivalents, beginning of period	738.4	669.2
Cash and cash equivalents, end of period	875.2	790.6
Supplemental cash flow information:
Cash paid for interest	7.5	9.2
Cash (received) paid for income taxes	(8.7)	0.9
Non-cash investing and financing activities:
Non-cash additions to property, plant and equipment	$ 5.4	$ 5.8

Organization and Business Descr

Organization and Business Description	3 Months Ended
	Mar. 31, 2020
Organization and Business Description
Organization and Business Description	1. Organization and Business Description United Therapeutics Corporation is a biotechnology company focused on the development and commercialization of innovative products to address the unmet medical needs of patients with chronic and life-threatening conditions. We have approval from the U.S. Food and Drug Administration (FDA) to market the following therapies: Remodulin ® ® ® ® ® As used in these notes to our consolidated financial statements, unless the context otherwise requires, the terms “we”, “us”, “our”, and similar terms refer to United Therapeutics Corporation and its consolidated subsidiaries.

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2020
Basis of Presentation
Basis of Presentation	2. 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. 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, 2019, as filed with the SEC on February 26, 2020. 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, 2020 and December 31, 2019, our statements of operations, comprehensive income, stockholders’ equity, and cash flows for the three-month periods ended March 31, 2020 and 2019. Interim results are not necessarily indicative of results for an entire year. Recently Issued Accounting Standards Accounting Standards Adopted During the Period In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement Accounting Standards Not Yet Adopted In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes , In January 2020, the FASB issued ASU 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)

Investments

Investments	3 Months Ended
	Mar. 31, 2020
Investments
Investments	3. 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 income in stockholders’ equity, until realized. Available-for-sale debt securities consisted of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair As of March 31, 2020 Cost ​ Gains Losses Value U.S. government and agency securities ​ $ 1,251.2 ​ $ 17.9 ​ $ (0.1) ​ $ 1,269.0 Corporate debt securities ​ ​ 244.7 ​ ​ 0.7 ​ ​ (0.9) ​ ​ 244.5 Total ​ $ 1,495.9 ​ $ 18.6 ​ $ (1.0) ​ $ 1,513.5 Reported under the following captions on our consolidated balance sheets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 645.5 Non-current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 868.0 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 1,513.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair As of December 31, 2019 Cost ​ Gains Losses Value U.S. government and agency securities ​ $ 1,225.2 ​ $ 2.9 ​ $ (0.2) ​ $ 1,227.9 Corporate debt securities ​ ​ 222.4 ​ ​ 1.7 ​ ​ — ​ ​ 224.1 Total ​ $ 1,447.6 ​ $ 4.6 ​ $ (0.2) ​ $ 1,452.0 Reported under the following captions on our consolidated balance sheets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 684.5 Non-current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 767.5 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 1,452.0 ​ The following table summarizes the contractual maturities of available-for-sale marketable investments (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, 2020 ​ Amortized Fair ​ Cost Value Due within one year ​ $ 641.3 ​ $ 645.5 Due in one to three years ​ ​ 854.6 ​ ​ 868.0 Total ​ $ 1,495.9 ​ $ 1,513.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ Amortized Fair ​ Cost Value Due within one year ​ $ 683.3 ​ $ 684.5 Due in one to three years ​ 764.3 ​ ​ 767.5 Total ​ $ 1,447.6 ​ $ 1,452.0 ​ Investments in Equity Securities with Readily Determinable Fair Values We held investments in equity securities with readily determinable fair values of $43.8 million and $63.0 million as of March 31, 2020 and December 31, 2019, 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 Investments Investments in Privately-Held Companies As of March 31, 2020 and December 31, 2019, we maintained non-controlling equity investments in privately-held companies of $102.9 million and $86.0 million, respectively, 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 quarter ended March 31, 2020, one of these privately-held companies raised additional capital by issuing equity securities similar to ours 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 quarter 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. One of these companies suspended operations during the quarter ended March 31, 2020, which caused us to recognize an impairment charge equal to the entire value of our investment in this company. The other company experienced a decline in its business arising from the negative effects of the COVID-19 pandemic during the quarter ended March 31, 2020, which caused us to recognize an impairment charge equal to a portion of the value of our investment in this company. 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 (VIE) In August 2019, we entered into an operating agreement and trust agreement related to the expected contribution of an asset to a newly created trust of which we are the beneficiary. The trust was created for legal and administrative purposes and is not expected to make future purchases. As the operator of the asset, we are required to incur all future expenses related to the operation and maintenance of the asset. Accordingly, the trust is deemed a VIE because it relies on our capital to pay future operating expenses. We are deemed the primary beneficiary of the VIE because we are the sole provider of financial support and can unilaterally remove the trustee without cause. Accordingly, we consolidate the VIE’s balance sheet and results of operations. As of March 31, 2020, our consolidated balance sheets included a $56.0 million asset within “property, plant, and equipment, net” due to the consolidation of this VIE. ​

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
Fair Value Measurements
Fair Value Measurements	4. Fair Value Measurements We 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, 2020 ​ Level 1 Level 2 Level 3 Balance Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (1) ​ $ 383.5 ​ $ — ​ $ — ​ $ 383.5 Time deposits (2) ​ ​ — ​ ​ 87.8 ​ ​ — ​ ​ 87.8 U.S. government and agency securities (3) ​ ​ — ​ ​ 1,269.0 ​ ​ — ​ ​ 1,269.0 Corporate debt securities (3) ​ — ​ 244.5 ​ — ​ 244.5 Equity securities (4) ​ ​ 43.8 ​ ​ — ​ ​ — ​ ​ 43.8 Total assets ​ $ 427.3 ​ $ 1,601.3 ​ $ — ​ $ 2,028.6 Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration (5) ​ — ​ — ​ 13.6 ​ 13.6 Total liabilities ​ $ — ​ $ — ​ $ 13.6 ​ $ 13.6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ Level 1 Level 2 Level 3 Balance Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (1) ​ $ 270.0 ​ $ — ​ $ — ​ $ 270.0 Time deposits (2) ​ ​ — ​ ​ 87.3 ​ ​ — ​ ​ 87.3 U.S. government and agency securities (3) ​ ​ — ​ ​ 1,227.9 ​ ​ — ​ ​ 1,227.9 Corporate debt securities (3) ​ — ​ 224.1 ​ — ​ 224.1 Equity securities (4) ​ ​ 63.0 ​ ​ — ​ ​ — ​ ​ 63.0 Total assets ​ $ 333.0 ​ $ 1,539.3 ​ $ — ​ $ 1,872.3 Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration (5) ​ — ​ — ​ 13.4 ​ 13.4 Total liabilities ​ $ — ​ $ — ​ $ 13.4 ​ $ 13.4 (1) Included in cash and cash equivalents on our consolidated balance sheets. (2) Included in cash and cash equivalents and current marketable investments on our consolidated balance sheets. The fair value of these securities is principally measured or corroborated by trade data for identical securities in which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (3) Included in cash and cash equivalents and current and non-current marketable investments on our consolidated balance sheets. Refer to Note 3 —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, 2020, we recognized $6.1 million of net unrealized and realized losses on these securities and recorded these losses on our consolidated statements of operations within “other income, net”. Refer to Note 3 —Investments—Investments in Equity Securities with Readily Determinable Fair Values. (5) 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, 2020 was not material. Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate fair value because of their short maturities. The fair values of our marketable investments and contingent consideration are reported above within the fair value hierarchy. Refer to Note 3 —Investments.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2020
Inventories
Inventories	5. 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, December 31, ​ ​ 2020 ​ 2019 Raw materials ​ $ 20.1 ​ $ 21.1 Work-in-progress ​ 28.1 ​ 29.1 Finished goods ​ 43.8 ​ 43.2 Total inventories ​ $ 92.0 ​ $ 93.4 ​

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2020
Goodwill and Other Intangible Assets
Goodwill and Other Intangible Assets	6. Goodwill and Other Intangible Assets Goodwill and other intangible assets comprise the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, 2020 ​ As of December 31, 2019 ​ ​ ​ Accumulated ​ ​ ​ ​ Accumulated ​ ​ ​ ​ Gross ​ Amortization ​ Net ​ Gross ​ Amortization ​ Net Goodwill ​ $ 28.0 ​ $ — ​ $ 28.0 ​ $ 28.0 ​ $ — ​ $ 28.0 Other intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ Technology, patents, and trade names ​ 6.7 ​ (5.3) ​ 1.4 ​ 6.7 ​ (5.3) ​ 1.4 In-process research and development (1) ​ 128.9 ​ — ​ 128.9 ​ 128.9 ​ — ​ 128.9 Total ​ $ 163.6 ​ $ (5.3) ​ $ 158.3 ​ $ 163.6 ​ $ (5.3) ​ $ 158.3 ​ (1) In April 2020, the FDA issued us a complete response letter related to our Trevyent ® new drug application (NDA). We determined this to be a potential indicator of impairment of our in-process research and development asset related to Trevyent, which had a carrying value of $107.3 million as of March 31, 2020. We have not yet finalized our impairment analysis, including the determination of fair value of the asset, but we may be required to impair some or all of the carrying value of this asset. ​

Debt

Debt	3 Months Ended
	Mar. 31, 2020
Debt
Debt	7. Debt Unsecured Revolving Credit Facility 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 accordance with the terms of the Credit Agreement, in June 2019, we extended the maturity date of the Credit Agreement by one year, to June 2024. The Credit Agreement provides the lenders the ability to extend the maturity date by one additional year, to June 2025, if we request such an extension. At our option, amounts borrowed under the 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 December 31, 2019, our outstanding aggregate principal balance was $850.0 million, of which $250.0 million was classified as a current liability because, as of such date, we intended to repay that amount within one year. During the three months ended March 31, 2020, we paid down $50.0 million of our balance under the Credit Agreement. This brought our aggregate outstanding balance to $800.0 million as of March 31, 2020, all of which was classified as a non-current liability because we no longer intend to repay any portion of this amount within one year. We decided not to repay a portion of the loan within one year out of an abundance of caution given the uncertainty surrounding the current COVID-19 pandemic and its potential impact on our business. The Credit Agreement contains customary events of default and customary affirmative and negative covenants. As of March 31, 2020, 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, 2020, $3.4 million was recorded in other current assets and $8.6 million in other non-current assets on our consolidated balance sheets. During the three months ended March 31, 2020 and March 31, 2019, we recorded interest expense of $8.2 million and $10.3 million, respectively, related to the Credit Agreement.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2020
Share-Based Compensation
Share-Based Compensation	8. Share-Based Compensation As of March 31, 2020, we have two shareholder-approved equity incentive plans: the United Therapeutics Corporation Amended and Restated Equity Incentive Plan (the 1999 Plan) and the United Therapeutics Corporation Amended and Restated 2015 Stock Incentive Plan (as amended to date, the 2015 Plan). The 2015 Plan provides for the issuance of up to 9,500,000 shares of our common stock pursuant to awards granted under the 2015 Plan, which includes the 450,000 shares added pursuant to an amendment and restatement of the 2015 Plan approved by our shareholders in June 2019. No further awards will be granted under the 1999 Plan. We also have one equity incentive plan, the United Therapeutics Corporation 2019 Inducement Stock Incentive Plan (the 2019 Inducement Plan), that has not been approved by our shareholders, as permitted by the Nasdaq Stock Market rules. The 2019 Inducement Plan was approved by our Board of Directors in February 2019 and provides for the issuance of up to 99,000 shares of our common stock under awards granted to newly-hired employees. Currently, we grant equity-based awards to employees and members of our Board of Directors in the form of stock options and restricted stock units under the 2015 Plan, and we grant restricted stock units to newly-hired employees under the 2019 Inducement Plan. Refer to the sections entitled Stock Options Restricted Stock Units We previously issued awards under the United Therapeutics Corporation Share Tracking Awards Plan (2008 STAP) and the United Therapeutics Corporation 2011 Share Tracking Awards Plan (2011 STAP). We refer to the 2008 STAP and the 2011 STAP collectively as the “STAP” and awards outstanding under either of these plans as “STAP awards.” Refer to the section entitled Share Tracking Awards Plans In 2012, our shareholders approved the United Therapeutics Corporation Employee Stock Purchase Plan (ESPP), which is structured to comply with Section 423 of the Internal Revenue Code. Refer to the section entitled Employee Stock Purchase Plan The following table reflects the components of share-based compensation expense recognized in our consolidated statements of operations (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2020 2019 Stock options ​ $ 16.4 ​ $ 15.7 Restricted stock units ​ 4.0 ​ 2.2 STAP awards ​ 10.1 ​ 11.0 Employee stock purchase plan ​ 0.3 ​ 0.3 Total share-based compensation expense before tax ​ $ 30.8 ​ $ 29.2 ​ 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, 2020 and March 31, 2019: ​ ​ ​ ​ ​ ​ ​ March 31, March 31, ​ ​ 2020 2019 ​ Expected term of awards (in years) 6.0 ​ 5.8 ​ Expected volatility 32.4 % 33.9 % Risk-free interest rate 0.8 % 2.4 % 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, 2020 is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted Average Aggregate ​ ​ ​ Average Remaining ​ Intrinsic ​ ​ Number of ​ Exercise ​ Contractual ​ Value ​ Options Price Term (in Years) (in millions) Outstanding at January 1, 2020 8,088,680 ​ $ 123.34 ​ ​ ​ ​ ​ Granted 16,599 ​ 91.91 ​ ​ ​ ​ ​ Exercised (13,500) ​ 51.77 ​ ​ ​ ​ ​ Forfeited/canceled (3,186) ​ 137.36 ​ ​ ​ ​ ​ Outstanding at March 31, 2020 8,088,593 ​ $ 123.39 6.1 ​ $ 15.6 Exercisable at March 31, 2020 5,219,099 ​ $ 124.25 5.4 ​ $ 14.3 Unvested at March 31, 2020 2,869,494 ​ $ 121.84 7.3 ​ $ 1.3 ​ The weighted average fair value of a stock option granted during each of the three-month periods ended March 31, 2020 and March 31, 2019, was $29.85 and $40.03, respectively. These stock options have an aggregate grant date fair value of $0.5 million and $80.5 million, respectively. The total grant date fair value of stock options that vested during the three-month periods ended March 31, 2020 and March 31, 2019 was $69.8 million and $33.7 million, respectively. Total share-based compensation expense relating to stock options is recorded as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ March 31, ​ 2020 2019 Cost of product sales ​ $ 0.2 $ 0.2 Research and development ​ 0.9 ​ 0.9 Selling, general, and administrative ​ 15.3 ​ 14.6 Share-based compensation expense before taxes ​ 16.4 ​ 15.7 Related income tax benefit ​ (3.7) ​ (3.5) Share-based compensation expense, net of taxes ​ $ 12.7 $ 12.2 ​ As of March 31, 2020, unrecognized compensation cost relating to stock options was $74.1 million. Unvested outstanding stock options as of March 31, 2020 had a weighted average remaining vesting period of 2.6 years. Stock option exercise data is summarized below (dollars in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ 2020 2019 Number of options exercised ​ 13,500 ​ 166,508 Cash received ​ $ 0.7 ​ $ 8.8 Total intrinsic value of options exercised ​ $ 0.6 ​ $ 10.3 ​ 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 the restricted stock units is recorded ratably over their vesting period. A summary of the activity with respect to, and status of, restricted stock units during the three-month period ended March 31, 2020 is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Weighted Average Aggregate ​ Number of Average Remaining Intrinsic ​ ​ Restricted Grant Date Contractual Value ​ ​ Stock Units ​ Fair Value Term (in Years) ​ (in millions) Unvested at January 1, 2020 310,725 ​ $ 112.24 ​ Granted 257,045 ​ 92.14 ​ Vested (104,818) ​ 114.92 ​ Forfeited/canceled (3,198) ​ 110.36 ​ Unvested at March 31, 2020 459,754 ​ $ 100.40 9.4 ​ $ 43.6 ​ Total share-based compensation expense relating to restricted stock units is recorded as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2020 2019 Cost of product sales $ 0.3 ​ $ 0.2 Research and development ​ 1.4 ​ 0.7 Selling, general, and administrative ​ 2.3 ​ 1.3 Share-based compensation expense before taxes ​ 4.0 ​ 2.2 Related income tax benefit ​ (0.9) ​ (0.5) Share-based compensation expense, net of taxes ​ $ 3.1 ​ $ 1.7 ​ As of March 31, 2020, unrecognized compensation cost related to the grant of restricted stock units was $43.5 million. Unvested outstanding restricted stock units as of March 31, 2020 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, and in most cases they vest in equal increments on each anniversary of the grant date over a four-year period. The aggregate STAP liability balance was $32.0 million and $25.0 million at March 31, 2020 and December 31, 2019, 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, March 31, ​ 2020 2019 ​ Expected term of awards (in years) 2.0 2.4 ​ Expected volatility 32.5 % 29.3 % Risk-free interest rate 0.2 % 2.2 % Expected dividend yield — % — % ​ The closing price of our common stock was $94.83 and $117.37 on March 31, 2020 and March 31, 2019, respectively. The closing price of our common stock was $88.08 on December 31, 2019. A summary of the activity and status of STAP awards during the three-month period ended March 31, 2020 is presented below: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Weighted Remaining Aggregate ​ ​ ​ Average Contractual Intrinsic ​ ​ Number of ​ Exercise Term ​ Value ​ ​ Awards ​ Price (in Years) ​ (in millions) Outstanding at January 1, 2020 2,622,328 ​ $ 109.10 ​ Granted — ​ — ​ Exercised (91,189) ​ 57.83 ​ Forfeited/canceled (5,875) ​ 103.88 ​ Outstanding at March 31, 2020 2,525,264 ​ $ 110.96 3.9 ​ $ 33.5 Exercisable at March 31, 2020 2,515,264 ​ $ 111.20 3.9 ​ $ 33.1 Unvested at March 31, 2020 10,000 ​ $ 52.57 2.7 ​ $ 0.4 ​ Share-based compensation expense recognized in connection with STAP awards is as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ March 31, ​ 2020 2019 Cost of product sales ​ $ 0.7 ​ $ 0.7 Research and development ​ 2.2 ​ 1.9 Selling, general, and administrative ​ 7.2 ​ 8.4 Share-based compensation expense before taxes ​ ​ 10.1 ​ ​ 11.0 Related income tax benefit ​ (2.3) ​ (2.5) Share-based compensation expense, net of taxes ​ $ 7.8 ​ $ 8.5 ​ Cash paid to settle STAP exercises during the three-month periods ended March 31, 2020 and March 31, 2019 was $3.0 million and $5.8 million, respectively. Employee Stock Purchase Plan In June 2012, our shareholders approved the ESPP, which is structured to comply with Section 423 of the Internal Revenue Code. The ESPP provides eligible employees with the right to purchase shares of our common stock at a discount through elective accumulated payroll deductions at the end of each offering period. Offering periods, which began in 2012, occur in consecutive six-month periods commencing on September 5th and March 5th of each year. Eligible employees may contribute up to 15 percent of their base salary, subject to certain annual limitations as defined in the ESPP. The purchase price of the shares is equal to the lower of 85 percent of the closing price of our common stock on either the first or last trading day of a given offering period. In addition, the ESPP provides that no eligible employee may purchase more than 4,000 shares during any offering period. The ESPP has a 20 -year term and limits the aggregate number of shares that can be issued under the ESPP to 3.0 million.

Earnings Per Common Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2020
Earnings Per Common Share.
Earnings Per Common Share	9. Earnings Per Common Share Basic earnings (loss) per common share is computed by dividing net income (loss) by the weighted average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the period, adjusted for the potential dilutive effect of our outstanding stock options, restricted stock units, and shares issuable under the ESPP, as if they were vested and exercised. For the three months ended March 31, 2019, we had a net loss, and as such, all outstanding stock options, restricted stock units, and shares issuable under the ESPP were excluded from our calculation of diluted loss per share. The components of basic and diluted earnings (loss) per common share comprised the following (in millions, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ 2020 2019 Numerator: ​ ​ ​ ​ ​ ​ Net income (loss) ​ $ 137.7 ​ $ (494.6) Denominator: ​ ​ ​ ​ ​ ​ Weighted average outstanding shares — basic ​ 43.9 ​ 43.7 Effect of dilutive securities (1) ​ ​ ​ ​ ​ ​ Stock options, restricted stock units and employee stock purchase plan ​ ​ 0.2 ​ ​ — Weighted average shares — diluted (2) ​ 44.1 ​ 43.7 Net income (loss) per common share: ​ ​ ​ ​ ​ ​ Basic ​ $ 3.14 ​ $ (11.32) Diluted ​ $ 3.12 ​ $ (11.32) ​ ​ ​ ​ ​ ​ ​ Stock options and restricted stock units excluded from calculation (2) ​ 7.6 ​ 5.3 (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, 2020 and March 31, 2019. For the three months ended March 31, 2019, shares issuable under the ESPP were also excluded.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2020
Income Taxes
Income Taxes	10. Income Taxes Our effective income tax rate (ETR) for the three months ended March 31, 2020 and 2019 was 20 percent and 24 percent, respectively. For the three months ended March 31, 2020, anticipated tax credits, state audit adjustments, and the foreign sales deduction, partially offset by non-deductible compensation and state tax expense, decreased our ETR. For the three months ended March 31, 2019, anticipated tax credits and the foreign sales deduction, partially offset by non-deductible compensation and state tax expense, increased our ETR due to the pre-tax loss that resulted primarily from the $800.0 million upfront payment under our license agreement with Arena Pharmaceuticals, Inc. As of March 31, 2020 and December 31, 2019, we had no unrecognized tax benefits. We record interest and penalties related to uncertain tax positions as a component of income tax expense. As of March 31, 2020 and December 31, 2019, we have not accrued any material interest expense related to uncertain tax positions. We are unaware of any material positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly increase within the next twelve months. On March 27, 2020, Congress enacted the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) to provide certain relief as a result of the COVID-19 pandemic. The CARES Act, among other things, includes provisions relating to net operating loss carryback periods, alternative minimum tax credit refunds, and modification to the net interest deduction limitations. The CARES Act did not have a material impact on our consolidated financial statements for the three months ended March 31, 2020. We continue to monitor any effects that may result from the CARES Act.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2020
Segment Information
Segment Information	11. Segment Information We currently operate as one operating segment with a focus on the development and commercialization of products to address the unmet needs of patients with chronic and life-threatening conditions. Our Chief Executive Officer, as our chief operating decision maker, manages and allocates resources to the operations of our company on a consolidated basis. This enables our Chief Executive Officer to assess our overall level of available resources and determine how best to deploy these resources across functions, therapeutic areas, and research and development projects in line with our long-term company-wide strategic goals. Net product sales, cost of product sales and gross profit for each of our commercial products were as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, 2020 Remodulin Tyvaso Orenitram Unituxin Adcirca Total 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 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net product sales ​ $ 155.5 ​ $ 103.8 ​ $ 58.4 ​ $ 24.9 ​ $ 20.0 ​ $ 362.6 Cost of product sales ​ 6.1 ​ 4.4 ​ 4.8 ​ 5.1 ​ 8.7 ​ 29.1 Gross profit ​ $ 149.4 ​ $ 99.4 ​ $ 53.6 ​ $ 19.8 ​ $ 11.3 ​ $ 333.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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, ​ 2020 2019 United States ​ $ 326.7 ​ $ 329.5 Rest-of-World (1) ​ 29.6 ​ 33.1 Total ​ $ 356.3 ​ $ 362.6 (1) Primarily Europe. We recorded revenue from two distributors in the United States that exceeded 10 percent of total revenues. Revenue from these two distributors as a percentage of total revenues is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ 2020 2019 Distributor 1 55 % 58 % Distributor 2 25 % 20 % ​

Litigation

Litigation	3 Months Ended
	Mar. 31, 2020
Litigation
Litigation	12. Litigation Sandoz Antitrust Litigation ​ On April 16, 2019, Sandoz Inc. (Sandoz) and its commercialization collaborator, RareGen, LLC, filed a complaint in the U.S. District Court for the District of New Jersey against us and Smiths Medical ASD, Inc. (Smiths Medical), alleging that we and Smiths Medical engaged in anticompetitive conduct in connection with plaintiffs’ efforts to launch their generic version of Remodulin. In particular, the complaint alleges that we and Smiths Medical unlawfully impeded competition by entering into an agreement to produce CADD-MS ® ​ On March 30, 2020, the plaintiffs filed an amended complaint in which Sandoz added a count alleging that we breached our earlier patent settlement agreement with Sandoz by refusing to grant Sandoz access to cartridges. We filed a motion to dismiss that count on April 17, 2020. ​ 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. ​ Liquidia Technologies, Inc. ​ On March 30, 2020, Liquidia Technologies, Inc. (Liquidia) filed two petitions for inter partes ​ 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 FDA had accepted its NDA and set a Prescription Drug User Fee Act (PDUFA) target action date of November 24, 2020. ​ 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 currently 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. We are currently reviewing the Notice Letter. We have 45 days from receipt of the Notice Letter to commence a patent infringement lawsuit against Liquidia to trigger a stay precluding FDA from approving Liquidia’s NDA for LIQ861 for up to 30 months or entry of judgment holding the patents invalid, unenforceable, or not infringed, whichever occurs first. ​ We plan to vigorously enforce our intellectual property rights related to Tyvaso.

Arena License Agreement

Arena License Agreement	3 Months Ended
	Mar. 31, 2020
Arena License Agreement
Arena License Agreement	13. Arena License Agreement On November 15, 2018, we entered into an exclusive license agreement with Arena related to ralinepag, a next-generation, oral, selective, and potent prostacyclin receptor agonist being developed for the treatment of PAH. On January 24, 2019, in connection with the closing of the transactions contemplated by the license agreement: (1) Arena granted to us perpetual, irrevocable, and exclusive rights throughout the universe to develop, manufacture, and commercialize ralinepag; (2) Arena transferred to us certain other assets related to ralinepag, including, among others, related domain names and trademarks, permits, certain contracts, inventory, regulatory documentation, Investigational New Drug (IND) Application No. 109021 (related to ralinepag), and nonclinical, pre-clinical and clinical trial data; (3) we assumed certain limited liabilities from Arena, including, among others, all obligations arising after the closing under the assumed contracts and the IND described above; and (4) we paid Arena an upfront payment of $800.0 million, which was expensed as acquired in-process research and development and included within research and development expenses on our consolidated statements of operations in the first quarter of 2019. We will also pay Arena: (1) a one-time payment of $250.0 million for the first, if any, marketing approval we receive in the United States for an inhaled version of ralinepag to treat PAH; (2) a one-time payment of $150.0 million for the first, if any, marketing approval we receive in any of Japan, France, Italy, the United Kingdom, Spain or Germany for an oral version of ralinepag to treat any indication; and (3) low double-digit, tiered royalties on net sales of any pharmaceutical product containing ralinepag as an active ingredient, subject to certain adjustments for third party license payments. ​

Basis of Presentation (Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2020
Basis of Presentation
Recently Issued Accounting Standards	Recently Issued Accounting Standards Accounting Standards Adopted During the Period In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement Accounting Standards Not Yet Adopted In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes , In January 2020, the FASB issued ASU 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)

Investments (Tables)

Investments (Tables) - Available-for-Sale Debt Securities	3 Months Ended
	Mar. 31, 2020
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 income in stockholders’ equity, until realized. Available-for-sale debt securities consisted of the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair As of March 31, 2020 Cost ​ Gains Losses Value U.S. government and agency securities ​ $ 1,251.2 ​ $ 17.9 ​ $ (0.1) ​ $ 1,269.0 Corporate debt securities ​ ​ 244.7 ​ ​ 0.7 ​ ​ (0.9) ​ ​ 244.5 Total ​ $ 1,495.9 ​ $ 18.6 ​ $ (1.0) ​ $ 1,513.5 Reported under the following captions on our consolidated balance sheets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 645.5 Non-current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 868.0 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 1,513.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ Fair As of December 31, 2019 Cost ​ Gains Losses Value U.S. government and agency securities ​ $ 1,225.2 ​ $ 2.9 ​ $ (0.2) ​ $ 1,227.9 Corporate debt securities ​ ​ 222.4 ​ ​ 1.7 ​ ​ — ​ ​ 224.1 Total ​ $ 1,447.6 ​ $ 4.6 ​ $ (0.2) ​ $ 1,452.0 Reported under the following captions on our consolidated balance sheets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 684.5 Non-current marketable investments ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 767.5 Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 1,452.0
Summary of the contractual maturities	The following table summarizes the contractual maturities of available-for-sale marketable investments (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, 2020 ​ Amortized Fair ​ Cost Value Due within one year ​ $ 641.3 ​ $ 645.5 Due in one to three years ​ ​ 854.6 ​ ​ 868.0 Total ​ $ 1,495.9 ​ $ 1,513.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ Amortized Fair ​ Cost Value Due within one year ​ $ 683.3 ​ $ 684.5 Due in one to three years ​ 764.3 ​ ​ 767.5 Total ​ $ 1,447.6 ​ $ 1,452.0

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Measurements
Schedule of assets and liabilities subject to fair value measurements	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, 2020 ​ Level 1 Level 2 Level 3 Balance Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (1) ​ $ 383.5 ​ $ — ​ $ — ​ $ 383.5 Time deposits (2) ​ ​ — ​ ​ 87.8 ​ ​ — ​ ​ 87.8 U.S. government and agency securities (3) ​ ​ — ​ ​ 1,269.0 ​ ​ — ​ ​ 1,269.0 Corporate debt securities (3) ​ — ​ 244.5 ​ — ​ 244.5 Equity securities (4) ​ ​ 43.8 ​ ​ — ​ ​ — ​ ​ 43.8 Total assets ​ $ 427.3 ​ $ 1,601.3 ​ $ — ​ $ 2,028.6 Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration (5) ​ — ​ — ​ 13.6 ​ 13.6 Total liabilities ​ $ — ​ $ — ​ $ 13.6 ​ $ 13.6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2019 ​ Level 1 Level 2 Level 3 Balance Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds (1) ​ $ 270.0 ​ $ — ​ $ — ​ $ 270.0 Time deposits (2) ​ ​ — ​ ​ 87.3 ​ ​ — ​ ​ 87.3 U.S. government and agency securities (3) ​ ​ — ​ ​ 1,227.9 ​ ​ — ​ ​ 1,227.9 Corporate debt securities (3) ​ — ​ 224.1 ​ — ​ 224.1 Equity securities (4) ​ ​ 63.0 ​ ​ — ​ ​ — ​ ​ 63.0 Total assets ​ $ 333.0 ​ $ 1,539.3 ​ $ — ​ $ 1,872.3 Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Contingent consideration (5) ​ — ​ — ​ 13.4 ​ 13.4 Total liabilities ​ $ — ​ $ — ​ $ 13.4 ​ $ 13.4 (1) Included in cash and cash equivalents on our consolidated balance sheets. (2) Included in cash and cash equivalents and current marketable investments on our consolidated balance sheets. The fair value of these securities is principally measured or corroborated by trade data for identical securities in which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (3) Included in cash and cash equivalents and current and non-current marketable investments on our consolidated balance sheets. Refer to Note 3 —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, 2020, we recognized $6.1 million of net unrealized and realized losses on these securities and recorded these losses on our consolidated statements of operations within “other income, net”. Refer to Note 3 —Investments—Investments in Equity Securities with Readily Determinable Fair Values. (5) 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, 2020 was not material.

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2020
Inventories
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, December 31, ​ ​ 2020 ​ 2019 Raw materials ​ $ 20.1 ​ $ 21.1 Work-in-progress ​ 28.1 ​ 29.1 Finished goods ​ 43.8 ​ 43.2 Total inventories ​ $ 92.0 ​ $ 93.4

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2020
Goodwill and Other Intangible Assets
Schedule of goodwill and other intangible assets	Goodwill and other intangible assets comprise the following (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, 2020 ​ As of December 31, 2019 ​ ​ ​ Accumulated ​ ​ ​ ​ Accumulated ​ ​ ​ ​ Gross ​ Amortization ​ Net ​ Gross ​ Amortization ​ Net Goodwill ​ $ 28.0 ​ $ — ​ $ 28.0 ​ $ 28.0 ​ $ — ​ $ 28.0 Other intangible assets: ​ ​ ​ ​ ​ ​ ​ ​ Technology, patents, and trade names ​ 6.7 ​ (5.3) ​ 1.4 ​ 6.7 ​ (5.3) ​ 1.4 In-process research and development (1) ​ 128.9 ​ — ​ 128.9 ​ 128.9 ​ — ​ 128.9 Total ​ $ 163.6 ​ $ (5.3) ​ $ 158.3 ​ $ 163.6 ​ $ (5.3) ​ $ 158.3 ​ (1) In April 2020, the FDA issued us a complete response letter related to our Trevyent ® new drug application (NDA). We determined this to be a potential indicator of impairment of our in-process research and development asset related to Trevyent, which had a carrying value of $107.3 million as of March 31, 2020. We have not yet finalized our impairment analysis, including the determination of fair value of the asset, but we may be required to impair some or all of the carrying value of this asset.

Share-Based Compensation (Table

Share-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Stock Options
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 March 31, ​ 2020 2019 Stock options ​ $ 16.4 ​ $ 15.7 Restricted stock units ​ 4.0 ​ 2.2 STAP awards ​ 10.1 ​ 11.0 Employee stock purchase plan ​ 0.3 ​ 0.3 Total share-based compensation expense before tax ​ $ 30.8 ​ $ 29.2 ​
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, 2020 and March 31, 2019: ​ ​ ​ ​ ​ ​ ​ March 31, March 31, ​ ​ 2020 2019 ​ Expected term of awards (in years) 6.0 ​ 5.8 ​ Expected volatility 32.4 % 33.9 % Risk-free interest rate 0.8 % 2.4 % Expected dividend yield — % — % ​
Schedule of activity and status of stock options	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted Average Aggregate ​ ​ ​ Average Remaining ​ Intrinsic ​ ​ Number of ​ Exercise ​ Contractual ​ Value ​ Options Price Term (in Years) (in millions) Outstanding at January 1, 2020 8,088,680 ​ $ 123.34 ​ ​ ​ ​ ​ Granted 16,599 ​ 91.91 ​ ​ ​ ​ ​ Exercised (13,500) ​ 51.77 ​ ​ ​ ​ ​ Forfeited/canceled (3,186) ​ 137.36 ​ ​ ​ ​ ​ Outstanding at March 31, 2020 8,088,593 ​ $ 123.39 6.1 ​ $ 15.6 Exercisable at March 31, 2020 5,219,099 ​ $ 124.25 5.4 ​ $ 14.3 Unvested at March 31, 2020 2,869,494 ​ $ 121.84 7.3 ​ $ 1.3 ​
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense relating to stock options is recorded as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ March 31, ​ 2020 2019 Cost of product sales ​ $ 0.2 $ 0.2 Research and development ​ 0.9 ​ 0.9 Selling, general, and administrative ​ 15.3 ​ 14.6 Share-based compensation expense before taxes ​ 16.4 ​ 15.7 Related income tax benefit ​ (3.7) ​ (3.5) Share-based compensation expense, net of taxes ​ $ 12.7 $ 12.2 ​
Summary of stock option exercise data	Stock option exercise data is summarized below (dollars in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ 2020 2019 Number of options exercised ​ 13,500 ​ 166,508 Cash received ​ $ 0.7 ​ $ 8.8 Total intrinsic value of options exercised ​ $ 0.6 ​ $ 10.3 ​
Restricted Stock Units
Share-Based Compensation
Schedule of restricted stock units activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ Weighted Average Aggregate ​ Number of Average Remaining Intrinsic ​ ​ Restricted Grant Date Contractual Value ​ ​ Stock Units ​ Fair Value Term (in Years) ​ (in millions) Unvested at January 1, 2020 310,725 ​ $ 112.24 ​ Granted 257,045 ​ 92.14 ​ Vested (104,818) ​ 114.92 ​ Forfeited/canceled (3,198) ​ 110.36 ​ Unvested at March 31, 2020 459,754 ​ $ 100.40 9.4 ​ $ 43.6 ​
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense relating to restricted stock units is recorded as follows (in millions): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ 2020 2019 Cost of product sales $ 0.3 ​ $ 0.2 Research and development ​ 1.4 ​ 0.7 Selling, general, and administrative ​ 2.3 ​ 1.3 Share-based compensation expense before taxes ​ 4.0 ​ 2.2 Related income tax benefit ​ (0.9) ​ (0.5) Share-based compensation expense, net of taxes ​ $ 3.1 ​ $ 1.7 ​
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 ​ March 31, ​ 2020 2019 Cost of product sales ​ $ 0.7 ​ $ 0.7 Research and development ​ 2.2 ​ 1.9 Selling, general, and administrative ​ 7.2 ​ 8.4 Share-based compensation expense before taxes ​ ​ 10.1 ​ ​ 11.0 Related income tax benefit ​ (2.3) ​ (2.5) Share-based compensation expense, net of taxes ​ $ 7.8 ​ $ 8.5 ​
Schedule of weighted-average assumptions to measure the fair value of outstanding STAP awards	​ ​ ​ ​ ​ ​ ​ ​ March 31, March 31, ​ 2020 2019 ​ Expected term of awards (in years) 2.0 2.4 ​ Expected volatility 32.5 % 29.3 % Risk-free interest rate 0.2 % 2.2 % Expected dividend yield — % — % ​
Summary of the activity and status of STAP awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Average ​ ​ ​ ​ ​ Weighted Remaining Aggregate ​ ​ ​ Average Contractual Intrinsic ​ ​ Number of ​ Exercise Term ​ Value ​ ​ Awards ​ Price (in Years) ​ (in millions) Outstanding at January 1, 2020 2,622,328 ​ $ 109.10 ​ Granted — ​ — ​ Exercised (91,189) ​ 57.83 ​ Forfeited/canceled (5,875) ​ 103.88 ​ Outstanding at March 31, 2020 2,525,264 ​ $ 110.96 3.9 ​ $ 33.5 Exercisable at March 31, 2020 2,515,264 ​ $ 111.20 3.9 ​ $ 33.1 Unvested at March 31, 2020 10,000 ​ $ 52.57 2.7 ​ $ 0.4 ​

Earnings Per Common Share (Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Common Share
Schedule of components of basic and diluted earnings (loss) per common share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ ​ March 31, ​ 2020 2019 Numerator: ​ ​ ​ ​ ​ ​ Net income (loss) ​ $ 137.7 ​ $ (494.6) Denominator: ​ ​ ​ ​ ​ ​ Weighted average outstanding shares — basic ​ 43.9 ​ 43.7 Effect of dilutive securities (1) ​ ​ ​ ​ ​ ​ Stock options, restricted stock units and employee stock purchase plan ​ ​ 0.2 ​ ​ — Weighted average shares — diluted (2) ​ 44.1 ​ 43.7 Net income (loss) per common share: ​ ​ ​ ​ ​ ​ Basic ​ $ 3.14 ​ $ (11.32) Diluted ​ $ 3.12 ​ $ (11.32) ​ ​ ​ ​ ​ ​ ​ Stock options and restricted stock units excluded from calculation (2) ​ 7.6 ​ 5.3 (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, 2020 and March 31, 2019. For the three months ended March 31, 2019, shares issuable under the ESPP were also excluded.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Information
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, 2020 Remodulin Tyvaso Orenitram Unituxin Adcirca Total 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 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2019 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net product sales ​ $ 155.5 ​ $ 103.8 ​ $ 58.4 ​ $ 24.9 ​ $ 20.0 ​ $ 362.6 Cost of product sales ​ 6.1 ​ 4.4 ​ 4.8 ​ 5.1 ​ 8.7 ​ 29.1 Gross profit ​ $ 149.4 ​ $ 99.4 ​ $ 53.6 ​ $ 19.8 ​ $ 11.3 ​ $ 333.5 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
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, ​ 2020 2019 United States ​ $ 326.7 ​ $ 329.5 Rest-of-World (1) ​ 29.6 ​ 33.1 Total ​ $ 356.3 ​ $ 362.6 (1) Primarily Europe.
Schedule of revenue from two specialty pharmaceutical distributors in the United States as a percentage of total revenue	​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ 2020 2019 Distributor 1 55 % 58 % Distributor 2 25 % 20 %

Basis of Presentation - Recentl

Basis of Presentation - Recently Issued Accounting Standards (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Recently Issued Accounting Standards
Decrease to retained earnings	$ (0.8)	$ (5.1)
ASU 2016-13
Recently Issued Accounting Standards
Decrease to retained earnings	0.8
Financing Receivable, Change in Present Value, Expense (Reversal)	1.1
Impairment charges	$ 1.5

Investments - Available-for-Sal

Investments - Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	$ 1,495.9	$ 1,447.6
Gross Unrealized Gains	18.6	4.6
Gross Unrealized Losses	(1)	(0.2)
Fair Value	1,513.5	1,452
U.S. government and agency securities
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	1,251.2	1,225.2
Gross Unrealized Gains	17.9	2.9
Gross Unrealized Losses	(0.1)	(0.2)
Fair Value	1,269	1,227.9
Corporate debt securities
Marketable investments classified as available-for-sale debt securities:
Amortized Cost	244.7	222.4
Gross Unrealized Gains	0.7	1.7
Gross Unrealized Losses	(0.9)
Fair Value	$ 244.5	$ 224.1

Investments - Current and Non-c

Investments - Current and Non-current of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Reported under the following captions on our consolidated balance sheet:
Total	$ 1,513.5	$ 1,452
Current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	645.5	684.5
Non-current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	$ 868	$ 767.5

Investments - Contractual Matur

Investments - Contractual Maturities of Available-for-Sale Marketable Investments (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Amortized Cost
Due within one year	$ 641.3	$ 683.3
Due in one to three years	854.6	764.3
Total	1,495.9	1,447.6
Fair Value
Due within one year	645.5	684.5
Due in one to three years	868	767.5
Total	$ 1,513.5	$ 1,452

Investments - Investments in Eq

Investments - Investments in Equity Securities with Readily Determinable Fair Values (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Equity securities
Investments in Equity Securities with Readily Determinable Fair Values
Investments in equity securities with readily determinable fair value	$ 43.8	$ 63

Investments - Investments in Pr

Investments - Investments in Privately-Held Companies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Investments in Privately-Held Companies and Investments in Equity Securities with Readily Determinable Fair Values
Impairments of investments in privately-held companies	$ 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	102.9	$ 86
Increase in the value of investment	$ 22.5

Investments - Variable Interest

Investments - Variable Interest Entity (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Variable Interest Entity
Assets	$ 4,025.9	$ 3,913.4
Property, Plant and Equipment [Member] | Variable Interest Entity
Variable Interest Entity
Assets	$ 56

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Recurring fair value measurements - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Equity securities | Other income (expense), net
Liabilities
Net unrealized and realized losses on securities	$ (6.1)
Level 1
Assets
Total assets	427.3	$ 333
Level 1 | Money market funds
Assets
Total assets	383.5	270
Level 1 | Equity securities
Assets
Total assets	43.8	63
Level 2
Assets
Total assets	1,601.3	1,539.3
Level 2 | Time deposits
Assets
Total assets	87.8	87.3
Level 2 | U.S. government and agency securities
Assets
Total assets	1,269	1,227.9
Level 2 | Corporate debt securities
Assets
Total assets	244.5	224.1
Level 3
Liabilities
Contingent consideration	13.6	13.4
Total liabilities	13.6	13.4
Balance
Assets
Total assets	2,028.6	1,872.3
Liabilities
Contingent consideration	13.6	13.4
Total liabilities	13.6	13.4
Balance | Money market funds
Assets
Total assets	383.5	270
Balance | Time deposits
Assets
Total assets	87.8	87.3
Balance | U.S. government and agency securities
Assets
Total assets	1,269	1,227.9
Balance | Corporate debt securities
Assets
Total assets	244.5	224.1
Balance | Equity securities
Assets
Total assets	$ 43.8	$ 63

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Inventories
Raw materials	$ 20.1	$ 21.1
Work-in-progress	28.1	29.1
Finished goods	43.8	43.2
Total inventories	$ 92	$ 93.4

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Goodwill and Other Intangible Assets
Goodwill, Gross	$ 28	$ 28
Goodwill, Net	28	28
Other intangible assets, Accumulated Amortization	(5.3)	(5.3)
Total Goodwill and other intangible assets, Gross	163.6	163.6
Total goodwill and other intangible assets, Net	158.3	158.3
Technology, patents and trade names
Goodwill and Other Intangible Assets
Other intangible assets, Gross	6.7	6.7
Other intangible assets, Accumulated Amortization	(5.3)	(5.3)
Other intangible assets, Net	1.4	1.4
In-process research and development
Goodwill and Other Intangible Assets
Other intangible assets, Gross	128.9	128.9
Other intangible assets, Accumulated Amortization		0
Other intangible assets, Net	128.9	$ 128.9
Carrying value of Trevyent intangible asset	$ 107.3

Debt (Details)

Debt (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Debt
Line of credit (current)				$ 250
Arena Pharmaceuticals, Inc.
Debt
Upfront payment			$ 800
Credit Agreement
Debt
Interest expense		$ 8.2	$ 10.3
Outstanding Balance				$ 850
Line of credit repaid during the period		50
Debt, maturity term	1 year
Repayment term				1 year
Credit Agreement | Current liabilities
Debt
Line of credit (current)				$ 250
Credit Agreement | Non-current liabilities
Debt
Outstanding Balance		800
First unsecured revolving credit facility
Debt
Borrowing		1,000
Second unsecured revolving credit facility
Debt
Borrowing		500
Increase in borrowing capacity		300
2018 Credit Agreement | Other current assets
Debt
Debt issuance costs capitalized		3.4
2018 Credit Agreement | Other non-current assets
Debt
Debt issuance costs capitalized		$ 8.6

Share-Based Compensation - Gene

Share-Based Compensation - General (Details)	1 Months Ended	3 Months Ended
	Feb. 28, 2019shares	Mar. 31, 2020itemshares
Share-Based Compensation
Number of equity incentive plans | item		2
2015 Plan
Share-Based Compensation
Maximum number of shares authorized to be issued		9,500,000
Additional number of shares authorized to be issued		450,000
2019 Inducement Plan | Newly-hired employees
Share-Based Compensation
Number of equity incentive plans | item		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, 2020	Mar. 31, 2019
Share-Based Compensation
Share-based compensation expense before tax	$ 30.8	$ 29.2
Stock Options
Share-Based Compensation
Share-based compensation expense before tax	16.4	15.7
Restricted Stock Units
Share-Based Compensation
Share-based compensation expense before tax	4	2.2
STAP awards
Share-Based Compensation
Share-based compensation expense before tax	10.1	11
Employee Stock Purchase Plan
Share-Based Compensation
Share-based compensation expense before tax	$ 0.3	$ 0.3

Share-Based Compensation - Assu

Share-Based Compensation - Assumptions For Stock Options (Details) - Stock Options	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Method and assumptions on valuation of stock options
Expected term of awards (in years)	6 years	5 years 9 months 18 days
Expected volatility (as a percent)	32.40%	33.90%
Risk-free interest rate (as a percent)	0.80%	2.40%

Share-Based Compensation - Stoc

Share-Based Compensation - Stock and Status (Details) - Stock Options - USD ($) $ / shares in Units, $ in Millions	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019
Options
Outstanding at beginning of the period (in shares)		8,088,680
Granted (in shares)		16,599
Exercised (in shares)		(13,500)	(166,508)
Forfeited/canceled (in shares)		(3,186)
Outstanding at the end of the period (in shares)	8,088,593	8,088,593
Exercisable at the end of the period (in shares)	5,219,099	5,219,099
Unvested at the end of the period (in shares)	2,869,494	2,869,494
Weighted Average Exercise Price
Outstanding at beginning of the period (in dollars per share)		$ 123.34
Granted (in dollars per share)		91.91
Exercised (in dollars per share)		51.77
Forfeited (in dollars per share)		137.36
Outstanding at the end of the period (in dollars per share)	$ 123.39	123.39
Exercisable at the end of the period (in dollars per share)	124.25	124.25
Unvested at the end of the period (in dollars per share)	$ 121.84	$ 121.84
Weighted Average Remaining Contractual Term (in Years)
Outstanding at the end of the period (in Years)	6 years 1 month 6 days
Exercisable at the end of the period (in Years)	5 years 4 months 24 days
Unvested at the end of the period (in Years)	7 years 3 months 18 days
Outstanding at the end of the period	$ 15.6	$ 15.6
Exercisable at the end of the period	14.3	14.3
Unvested at the end of the period	$ 1.3	$ 1.3
Share-based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value Disclosures [Abstract]
Weighted average grant date fair value of stock options (in dollars per share)		$ 29.85	$ 40.03
Aggregate grant date fair value		$ 0.5	$ 80.5
Total grant date fair value of employee stock options that vested		$ 69.8	$ 33.7

Share-Based Compensation - Shar

Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based compensation expense
Share-based compensation expense before tax	$ 30.8	$ 29.2
Stock Options
Share-based compensation expense
Share-based compensation expense before tax	16.4	15.7
Related income tax benefit	(3.7)	(3.5)
Share-based compensation expense, net of tax	12.7	12.2
Unrecognized compensation cost	$ 74.1
Weighted average remaining vesting period (in years)	2 years 7 months 6 days
Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	$ 4	2.2
Related income tax benefit	(0.9)	(0.5)
Share-based compensation expense, net of tax	3.1	1.7
Unrecognized compensation cost	$ 43.5
Weighted average remaining vesting period (in years)	2 years 4 months 24 days
Cost of product sales | Stock Options
Share-based compensation expense
Share-based compensation expense before tax	$ 0.2	0.2
Cost of product sales | Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	0.3	0.2
Research and development | Stock Options
Share-based compensation expense
Share-based compensation expense before tax	0.9	0.9
Research and development | Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	1.4	0.7
Selling, general, and administrative | Stock Options
Share-based compensation expense
Share-based compensation expense before tax	15.3	14.6
Selling, general, and administrative | Restricted Stock Units
Share-based compensation expense
Share-based compensation expense before tax	$ 2.3	$ 1.3

Share-Based Compensation - St_2

Share-Based Compensation - Stock Options Exercise Data (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Summary of stock option exercise data
Cash received	$ 0.7	$ 8.8
Stock Options
Summary of stock option exercise data
Number of options exercised (in shares)	13,500	166,508
Cash received	$ 0.7	$ 8.8
Total intrinsic value of options exercised	$ 0.6	$ 10.3

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Options Activity and Status (Details) - Restricted Stock Units $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)item$ / sharesshares
Share-Based Compensation
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Entitled To Receive For Each Unit Upon Vesting | item	1
Number of Restricted Stock Units
Unvested at beginning of the period (in shares) | shares	310,725
Granted (in shares) | shares	257,045
Vested (in shares) | shares	(104,818)
Forfeited/cancelled (in shares) | shares	(3,198)
Unvested at the end of the period (in shares) | shares	459,754
Weighted-Average Grant Date Fair Value
Unvested at beginning of the period (in dollars per share) | $ / shares	$ 112.24
Granted (in dollars per share) | $ / shares	92.14
Vested (in dollars per share) | $ / shares	114.92
Forfeited/cancelled (in dollars per share) | $ / shares	110.36
Unvested at the end of the period (in dollars per share) | $ / shares	$ 100.40
Weighted Average Remaining Contractual Term (Years)
Outstanding at the end of the period (in Years)	9 years 4 months 24 days
Aggregate Intrinsic Value
Unvested at the end of the period (in dollars) | $	$ 43.6

Share-Based Compensation - STAP

Share-Based Compensation - STAP awards (Details) - STAP awards - USD ($) $ / shares in Units, $ in Millions	Mar. 31, 2020	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Awards granted
Grant expiration period from the grant date		4 years
Aggregate STAP liability	$ 32	$ 32		$ 25
Weighted-average assumptions used to measure the fair value of the outstanding STAP awards:
Expected term of awards (in years)		2 years	2 years 4 months 24 days
Expected volatility (as a percent)		32.50%	29.30%
Risk-free interest rate (as a percent)		0.20%	2.20%
Closing price of common stock (in dollars per share)	$ 94.83	$ 94.83	$ 117.37	$ 88.08
Share-based awards activity
Outstanding at January 1, 2020		2,622,328
Exercised (in shares)		(91,189)
Forfeited/cancelled (in shares)		(5,875)
Outstanding at March 31, 2020	2,525,264	2,525,264
Exercisable at March 31, 2020	2,515,264	2,515,264
Unvested at March 31, 2020	10,000	10,000
Share awards, Weighted-Average Exercise Price
Outstanding at January 1, 2020		$ 109.10
Exercised (in dollars per share)	$ 57.83	57.83
Forfeited (in dollars per share)	103.88	103.88
Outstanding at March 31, 2020	110.96	110.96
Exercisable at March 31, 2020	111.20	111.20
Unvested at March 31, 2020	$ 52.57	$ 52.57
Share awards, Weighted Average Remaining Contractual Term (in Years)
Outstanding at March 31, 2020	3 years 10 months 24 days
Exercisable at March 31, 2020	3 years 10 months 24 days
Unvested at March 31, 2020	2 years 8 months 12 days
Share awards, Aggregate Intrinsic Value
Outstanding at March 31, 2020	$ 33.5	$ 33.5
Exercisable at March 31, 2020	33.1	33.1
Unvested at March 31, 2020	$ 0.4	$ 0.4

Share-Based Compensation - Sh_2

Share-Based Compensation - Share Tracking Awards Plans - Benefit recognized (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax	$ 30.8	$ 29.2
STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax	10.1	11
Related income tax benefit	(2.3)	(2.5)
Share-based compensation expense, net of tax	7.8	8.5
Cash payments on awards exercised during the period	3	5.8
Cost of product sales | STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax	0.7	0.7
Research and development | STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax	2.2	1.9
Selling, general, and administrative | STAP awards
Share based compensation (benefit) expense recognized in connection with the STAP
Share-based compensation expense before tax	$ 7.2	$ 8.4

Share-Based Compensation - Empl

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

Earnings Per Common Share (Deta

Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income (loss)	$ 137.7	$ (494.6)
Denominator:
Weighted average outstanding shares - basic (in shares)	43.9	43.7
Effect of dilutive securities:
Stock options, restricted stock units and employee stock purchase plan (in shares)	0.2
Weighted average shares - diluted (in shares)	44.1	43.7
Net income (loss) per common share:
Basic (in dollars per share)	$ 3.14	$ (11.32)
Diluted (in dollars per share)	$ 3.12	$ (11.32)
Stock options and restricted stock units excluded from calculation (in shares)	7.6	5.3

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Effective income tax rate (as a percent)	20.00%	24.00%
Unrecognized tax benefits	$ 0		$ 0
Interest expense related to uncertain tax positions	$ 0		$ 0
Arena Pharmaceuticals, Inc.
Upfront payment		$ 800

Segment Information - General (

Segment Information - General (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020USD ($)segment	Mar. 31, 2019USD ($)
Net product sales, cost of product sales and gross profit by product
Net product sales	$ 356.3	$ 362.6
Cost of product sales	23.4	29.1
Gross profit	$ 332.9	333.5
Segment disclosures
Number of operating segments | segment	1
Remodulin
Net product sales, cost of product sales and gross profit by product
Net product sales	$ 145.3	155.5
Cost of product sales	6	6.1
Gross profit	139.3	149.4
Tyvaso
Net product sales, cost of product sales and gross profit by product
Net product sales	102.9	103.8
Cost of product sales	5.1	4.4
Gross profit	97.8	99.4
Orenitram
Net product sales, cost of product sales and gross profit by product
Net product sales	69	58.4
Cost of product sales	4.7	4.8
Gross profit	64.3	53.6
Unituxin
Net product sales, cost of product sales and gross profit by product
Net product sales	26.6	24.9
Cost of product sales	2.3	5.1
Gross profit	24.3	19.8
Adcirca
Net product sales, cost of product sales and gross profit by product
Net product sales	12.5	20
Cost of product sales	5.3	8.7
Gross profit	$ 7.2	$ 11.3

Segment Information - Geographi

Segment Information - Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues from external customers by geographic area
Total revenues	$ 356.3	$ 362.6
United States
Revenues from external customers by geographic area
Total revenues	326.7	329.5
Rest-of-World
Revenues from external customers by geographic area
Total revenues	$ 29.6	$ 33.1

Segment Information - Concentra

Segment Information - Concentration Risk (Details) - item	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Information
Number of distributors	2
Net revenues | Customer concentration | Customer one
Segment Information
Concentration risk, percentage	55.00%	58.00%
Net revenues | Customer concentration | Customer two
Segment Information
Concentration risk, percentage	25.00%	20.00%

Litigation (Details)

Litigation (Details) - Liquidia Technologies, Inc. [Member] - item	Apr. 27, 2020	Mar. 30, 2020
Litigation
Maximum period for which the FDA is automatically precluded from approving ANDA	30 months
Number of petitions		2
Time period to file a preliminary response to the petitions	45 days
Time period to choose to file a response		3 months

Arena License Agreement (Detail

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