Ironwood Pharmaceuticals (IRWD) 10-Q 5 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	6 Months Ended
	Jun. 30, 2021	Jul. 31, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	001-34620
Entity Registrant Name	IRONWOOD PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3404176
Entity Address, Address Line One	100 Summer Street
Entity Address, Address Line Two	Suite 2300
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02110
City Area Code	617
Local Phone Number	621-7722
Title of 12(b) Security	Class A common stock, $0.001 par value
Entity Listing, Par Value Per Share	$ 0.001
Trading Symbol	IRWD
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		162,895,011
Entity Central Index Key	0001446847
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 492,699	$ 362,564
Accounts receivable, net	102,252	122,351
Prepaid expenses and other current assets	12,320	9,189
Restricted cash	1,735	1,735
Convertible note hedges	11,262
Total current assets	620,268	495,839
Restricted cash, net of current portion	485	485
Accounts receivable, net of current portion	23,706	23,401
Property and equipment, net	8,105	8,929
Operating lease right-of-use assets	15,975	16,576
Convertible note hedges		13,065
Deferred tax assets	337,800
Other assets	879	943
Total assets	1,007,218	559,238
Current liabilities:
Accounts payable	466	661
Accrued research and development costs	1,638	1,898
Accrued expenses and other current liabilities	16,253	26,486
Current portion of operating lease liabilities	3,161	3,128
Current portion of convertible senior notes	112,852
Total current liabilities	134,370	32,173
Note hedge warrants	11,061	12,088
Convertible senior notes, net of current portion	329,155	430,256
Operating lease obligations, net of current portion	19,394	20,318
Other liabilities	1,482	1,763
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value, 75,000,000 shares authorized, no shares issued and outstanding
Class A Common Stock, $0.001 par value, 500,000,000 shares authorized and 162,831,953 shares issued and outstanding at June 30, 2021 and 500,000,000 shares authorized and 160,616,675 shares issued and outstanding at December 31, 2020	163	161
Additional paid-in capital	1,546,420	1,528,535
Accumulated deficit	(1,034,827)	(1,466,056)
Total stockholders' equity	511,756	62,640
Total liabilities and stockholders' equity	$ 1,007,218	$ 559,238

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Preferred stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	75,000,000	75,000,000
Preferred stock, shares issued		0
Preferred stock, shares outstanding	0	0
Common stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	162,831,953	160,616,675
Common stock, shares outstanding	162,831,953	160,616,675

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Total revenues	$ 104,031	$ 89,432	$ 192,876	$ 169,375
Cost and expenses:
Cost of revenues				2,239
Research and development	12,163	22,076	27,647	50,103
Selling, general and administrative	27,052	34,643	54,704	71,093
Restructuring expenses	(282)		29
Total cost and expenses	38,933	56,719	82,380	123,435
Income from operations	65,098	32,713	110,496	45,940
Other (expense) income:
Interest expense	(7,732)	(7,318)	(15,358)	(14,538)
Interest and investment income	172	276	368	1,053
Loss on derivatives	(3,166)	(467)	(776)	(3,933)
Other income				27
Other expense, net	(10,726)	(7,509)	(15,766)	(17,391)
Income before income taxes	54,372	25,204	94,730	28,549
Income tax benefit	336,931	0	336,499	0
Net income	391,303	25,204	431,229	28,549
Comprehensive income	$ 391,303	$ 25,204	$ 431,229	$ 28,549
Net income per share - basic (in dollars per share)	$ 2.42	$ 0.16	$ 2.67	$ 0.18
Net income per share - diluted (in dollars per share)	$ 2.39	$ 0.16	$ 2.64	$ 0.18
Weighted average shares used in computing net income per share - basic: (in shares)	161,948	159,407	161,460	158,890
Weighted average shares used in computing net income per share - diluted: (in shares)	163,495	159,920	163,134	160,032
Collaborative arrangements revenue
Revenues:
Total revenues	$ 103,386	$ 89,423	$ 192,051	$ 163,868
Sale of active pharmaceutical ingredient
Revenues:
Total revenues	$ 645	$ 9	$ 825	$ 5,507

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock	Additional paid-in capital	Accumulated deficit	Total
Balance at Dec. 31, 2019	$ 158	$ 1,478,823	$ (1,572,232)	$ (93,251)
Balance (in shares) at Dec. 31, 2019	157,535,962
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to share-based awards and employee stock purchase plan	$ 1	11,984		11,985
Issuance of common stock related to share-based awards and employee stock purchase plan (in shares)	1,832,164
Share-based compensation expense related to share-based awards and employee stock purchase plan		6,364		6,364
Net income			3,345	3,345
Balance at Mar. 31, 2020	$ 159	1,497,171	(1,568,887)	(71,557)
Balance (in shares) at Mar. 31, 2020	159,368,126
Balance at Dec. 31, 2019	$ 158	1,478,823	(1,572,232)	(93,251)
Balance (in shares) at Dec. 31, 2019	157,535,962
Increase (Decrease) in Stockholders' Equity
Net income				28,549
Balance at Jun. 30, 2020	$ 160	1,506,671	(1,543,683)	(36,852)
Balance (in shares) at Jun. 30, 2020	159,976,245
Balance at Mar. 31, 2020	$ 159	1,497,171	(1,568,887)	(71,557)
Balance (in shares) at Mar. 31, 2020	159,368,126
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to share-based awards and employee stock purchase plan	$ 1	2,409		2,410
Issuance of common stock related to share-based awards and employee stock purchase plan (in shares)	608,119
Share-based compensation expense related to share-based awards and employee stock purchase plan		7,091		7,091
Net income			25,204	25,204
Balance at Jun. 30, 2020	$ 160	1,506,671	(1,543,683)	(36,852)
Balance (in shares) at Jun. 30, 2020	159,976,245
Balance at Dec. 31, 2020	$ 161	1,528,535	(1,466,056)	$ 62,640
Balance (in shares) at Dec. 31, 2020	160,616,675			160,616,675
Increase (Decrease) in Stockholders' Equity
Share-based compensation expense related to share-based awards and employee stock purchase plan		5,396		$ 5,396
Net income			39,926	39,926
Balance at Mar. 31, 2021	$ 162	1,536,160	(1,426,130)	110,192
Balance (in shares) at Mar. 31, 2021	161,931,012
Balance at Dec. 31, 2020	$ 161	1,528,535	(1,466,056)	$ 62,640
Balance (in shares) at Dec. 31, 2020	160,616,675			160,616,675
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to share-based awards and employee stock purchase plan	$ 1	2,229		$ 2,230
Issuance of common stock related to share-based awards and employee stock purchase plan (in shares)	1,314,337
Net income				431,229
Balance at Jun. 30, 2021	$ 163	1,546,420	(1,034,827)	$ 511,756
Balance (in shares) at Jun. 30, 2021	162,831,953			162,831,953
Balance at Mar. 31, 2021	$ 162	1,536,160	(1,426,130)	$ 110,192
Balance (in shares) at Mar. 31, 2021	161,931,012
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to share-based awards and employee stock purchase plan	$ 1	5,671		5,672
Issuance of common stock related to share-based awards and employee stock purchase plan (in shares)	900,941
Share-based compensation expense related to share-based awards and employee stock purchase plan		4,589		4,589
Net income			391,303	391,303
Balance at Jun. 30, 2021	$ 163	$ 1,546,420	$ (1,034,827)	$ 511,756
Balance (in shares) at Jun. 30, 2021	162,831,953			162,831,953

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 431,229	$ 28,549
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	806	1,322
Loss on disposal of property and equipment	17	423
Share-based compensation expense	9,985	13,455
Change in fair value of note hedge warrants	(1,027)	(11,302)
Change in fair value of convertible note hedges	1,803	15,235
Non-cash interest expense	11,750	10,930
Deferred income taxes (including benefit from valuation allowance release)	(337,800)
Changes in assets and liabilities:
Accounts receivable and related party accounts receivable, net	19,794	21,469
Prepaid expenses and other current assets	(3,101)	(3,638)
Inventory, net		648
Operating lease right-of-use assets	601	587
Other assets	64	(30)
Accounts payable, related party accounts payable and accrued expenses	(10,428)	(13,861)
Accrued research and development costs	(260)	(556)
Operating lease liabilities	(891)	593
Other liabilities	(280)	(133)
Net cash provided by operating activities	122,262	63,691
Cash flows from investing activities:
Purchases of property and equipment		(1,814)
Net cash used in investing activities		(1,814)
Cash flows from financing activities:
Proceeds from exercise of stock options and employee stock purchase plan	7,873	14,352
Net cash provided by financing activities	7,873	14,352
Net increase in cash, cash equivalents and restricted cash	130,135	76,229
Cash, cash equivalents and restricted cash, beginning of period	364,784	179,244
Cash, cash equivalents and restricted cash, end of period	$ 494,919	$ 255,473

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Reconciliation of cash, cash equivalents, and restricted cash to the condensed consolidated balance sheets
Cash and cash equivalents	$ 492,699	$ 362,564	$ 253,252
Restricted cash	2,220		2,221
Total cash, cash equivalents, and restricted cash	$ 494,919	$ 364,784	$ 255,473	$ 179,244

Nature of Business

Nature of Business	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Nature of Business	1. Nature of Business ​ Ironwood Pharmaceuticals, Inc. (“Ironwood” or the “Company”) is a gastrointestinal (“GI”) healthcare company dedicated to advancing the treatment of GI diseases and redefining the standard of care for GI patients. The Company is focused on the development and commercialization of innovative GI product opportunities in areas of significant unmet need, leveraging its demonstrated expertise and capabilities in GI diseases. ​ LINZESS ® ® to adult men and women suffering from IBS-C or CIC in Canada, and to adult men and women suffering from IBS-C in certain European countries. ​ The Company has strategic partnerships with leading pharmaceutical companies to support the development and commercialization of linaclotide throughout the world. The Company and its partner, AbbVie Inc. (together with its affiliates, “AbbVie”) (successor to Allergan plc), began commercializing LINZESS in the U.S. in December 2012. AbbVie AbbVie AbbVie AbbVie AbbVie AbbVie AbbVie AbbVie ​ Astellas Pharma Inc. (“Astellas”), the Company’s partner in Japan, has an exclusive license to develop and commercialize linaclotide in Japan. In March 2017, Astellas began commercializing LINZESS for the treatment of adults with IBS-C in Japan, and in September 2018, Astellas began commercializing LINZESS for the treatment of adults with chronic constipation in Japan. In August 2019, the Company amended and restated its license agreement with Astellas. Effective in 2020, the Company is no longer responsible for the supply of linaclotide active pharmaceutical ingredient (“API”) to Astellas (Note 4). ​ In October 2012, the Company and AstraZeneca AB (together with its affiliates) (“AstraZeneca”) entered into a collaboration agreement to co-develop and co-commercialize linaclotide in China (including Hong Kong and Macau) (the “AstraZeneca License Territory”). In September 2019, the Company amended and restated its existing collaboration agreement with AstraZeneca whereby AstraZeneca obtained the exclusive right to develop, manufacture, and commercialize products containing linaclotide in the AstraZeneca License Territory (Note 4). In November 2019, AstraZeneca began commercializing LINZESS for the treatment of adults with IBS-C in China. ​ The Company and AbbVie are exploring ways to enhance the clinical profile of LINZESS by studying linaclotide in additional indications, populations and formulations to assess its potential to treat various conditions. In September 2020, based on the Phase IIIb data demonstrating efficacy and safety of LINZESS 290 mcg on the overall abdominal symptoms of bloating, pain and discomfort in adult patients with IBS-C, the U.S. FDA approved the Company’s supplemental New Drug Application to include a more comprehensive description of the effects of LINZESS in its approved label. In June 2020 and July 2020, the United States Patent and Trademark Office granted patents covering the formulation of the 72 mcg dose of LINZESS and methods of using the formulation, respectively. The patents are expected to expire in 2031. ​ ​ These and other agreements are more fully described in Note 4, Collaboration, License, Promotion and Other Commercial Agreements ​ On April 1, 2019, Ironwood completed the separation (the “Separation”) of its soluble guanylate cyclase business, and certain other assets and liabilities, into Cyclerion Therapeutics, Inc. (“Cyclerion”). The Separation was effected by means of a distribution of all of the outstanding shares of common stock, with no par value, of Cyclerion through a dividend of all outstanding shares of Cyclerion’s common stock, to Ironwood’s stockholders of record as of the close of business on March 19, 2019.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies ​ Basis of Presentation ​ The accompanying condensed consolidated financial statements and the related disclosures are unaudited and have been prepared in accordance with accounting principles generally accepted in the U.S. Additionally, certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, which was filed with the Securities and Exchange Commission on February 17, 2021 (the “2020 Annual Report on Form 10-K”). ​ The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all normal recurring adjustments considered necessary for a fair statement of the Company’s financial position as of June 30, 2021, and the results of its operations for the three and six months ended June 30, 2021 and 2020, its statements of stockholders’ equity for the three and six months ended June 30, 2021 and 2020, and its cash flows for the six months ended June 30, 2021 and 2020. The results of operations for the three and six months ended June 30, 2021 and 2020 are not necessarily indicative of the results that may be expected for the full year or any other subsequent interim period. ​ Principles of Consolidation ​ The accompanying condensed consolidated financial statements include the accounts of Ironwood and its wholly-owned subsidiaries as of June 30, 2021, Ironwood Pharmaceuticals Securities Corporation and Ironwood Pharmaceuticals GmbH. All intercompany transactions and balances are eliminated in consolidation. ​ Use of Estimates ​ The preparation of condensed consolidated financial statements in accordance with U.S. generally accepted accounting principles requires the Company’s management to make estimates and judgments that may affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the amounts of revenues and expenses during the reported periods. On an ongoing basis, the Company’s management evaluates its estimates, judgments and methodologies. Significant estimates and assumptions in the condensed consolidated financial statements include those related to revenue recognition; accounts receivable; useful lives of long-lived assets, impairment of long-lived assets, including goodwill; valuation procedures for right-of-use assets and operating lease liabilities; valuation procedures for the issuance and repurchase of convertible notes; balance sheet classification of convertible notes; fair value of derivatives; income taxes, including the valuation allowance for deferred tax assets; research and development expenses; contingencies and share-based compensation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ materially from these estimates under different assumptions or conditions. Changes in estimates are reflected in reported results in the period in which they become known. Reclassifications ​ ​ Summary of Significant Accounting Policies ​ The Company’s significant accounting policies are described in Note 2, Summary of Significant Accounting Policies ​ New Accounting Pronouncements ​ From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (the “FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. ​ In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , ​ In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging— Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity In May 2021, the FASB issued ASU No. 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options Other recent accounting pronouncements issued, but not yet effective, are not expected to be applicable to the Company or have a material effect on the condensed consolidated financial statements upon future adoption. ​ ​

Net Income Per Share

Net Income Per Share	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Net Income Per Share	​ 3. Net Income Per Share ​ The following table sets forth the computation of basic and diluted net income per common share (in thousands, except per share amounts): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2021 2020 ​ 2021 ​ 2020 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 391,303 ​ $ 25,204 ​ $ 431,229 ​ $ 28,549 Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average number of common shares outstanding used in computing net income per share — basic ​ ​ 161,948 ​ ​ 159,407 ​ 161,460 ​ 158,890 Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Stock options ​ ​ 417 ​ ​ 244 ​ ​ 348 ​ ​ 465 Time-based restricted stock units ​ ​ 928 ​ ​ 153 ​ ​ 1,121 ​ ​ 552 Performance-based restricted stock units ​ ​ 70 ​ ​ — ​ ​ 71 ​ ​ — Restricted stock ​ ​ 132 ​ ​ 116 ​ ​ 134 ​ ​ 125 Dilutive potential common shares ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average number of common shares outstanding used in computing net income per share — diluted ​ ​ 163,495 ​ ​ 159,920 ​ ​ 163,134 ​ 160,032 Net income per share — basic ​ $ 2.42 ​ $ 0.16 ​ $ 2.67 ​ $ 0.18 Net income per share — diluted ​ $ 2.39 ​ $ 0.16 ​ $ 2.64 ​ $ 0.18 ​ ​ The outstanding securities have been excluded from the computation of diluted weighted average shares outstanding, as applicable, as their effect would be anti-dilutive (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2021 2020 ​ 2021 2020 Stock options ​ 9,430 ​ 12,360 ​ 10,007 14,828 ​ Restricted stock awards — ​ — ​ 36 — ​ Shares subject to repurchase ​ — ​ — ​ — ​ 174 ​ Time-based restricted stock units ​ 84 ​ 3,134 ​ 53 ​ 5,012 ​ Performance-based restricted stock units ​ 619 ​ — ​ 330 ​ 586 ​ Note Hedge Warrants ​ 8,318 ​ 8,318 ​ 8,318 ​ 8,318 ​ 2022 Convertible Notes ​ 8,318 ​ 8,318 ​ 8,318 ​ 8,318 ​ 2024 Convertible Notes ​ 14,934 ​ 14,934 ​ 14,934 ​ 14,934 ​ 2026 Convertible Notes ​ 14,934 ​ 14,934 ​ 14,934 ​ 14,934 ​ Total 56,637 61,998 ​ 56,930 67,104 ​ ​ ​ The potentially dilutive impact of the 2022 Convertible Notes, 2024 Convertible Notes and 2026 Convertible notes (together, the “Convertible Senior Notes”) (Note 8) is determined using the treasury stock method. Under this method, no numerator or denominator adjustments arise from the principal and interest components of the Convertible Senior Notes because the Company has the intent and ability to settle the Convertible Senior Notes’ principal and interest in cash. Instead, the Company is required to increase the diluted net income per share denominator by the variable number of shares that would be issued upon conversion if it settled the conversion spread obligation with shares. For diluted net income per share purposes, the conversion spread obligation is calculated based on whether the average market price of the Company’s Class A Common Stock during the reporting period is in excess of the conversion price of the Convertible Senior Notes. There was no calculated spread added to the denominator for the three and six months ended June 30, 2021 or 2020.

Collaboration, License, Promoti

Collaboration, License, Promotion and Other Commercial Agreements	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Collaboration, License, Promotion and Other Commercial Agreements	4. Collaboration, License, Promotion and Other Commercial Agreements ​ For the three and six months ended June 30, 2021, the Company had linaclotide collaboration agreements with AbbVie for North America and AstraZeneca for China (including Hong Kong and Macau), as well as linaclotide license agreements with Astellas for Japan and with AbbVie for the AbbVie License Territory. The Company also had an agreement with Alnylam Pharmaceuticals, Inc (“Alnylam”) to perform disease awareness activities for AHP and sales detailing activities for GIVLAARI. The following table provides amounts included in the Company’s consolidated statements of income as collaborative arrangements revenue and sale of API primarily attributable to transactions from these arrangements (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, Collaborative Arrangements Revenue ​ 2021 2020 ​ 2021 2020 Linaclotide Collaboration and License Agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AbbVie (North America) ​ $ 101,038 ​ $ 86,926 ​ $ 187,537 ​ $ 158,618 AbbVie (Europe and other) ​ ​ 574 ​ ​ 440 ​ ​ 1,174 ​ ​ 1,083 AstraZeneca (China, including Hong Kong and Macau) ​ ​ 200 ​ 187 ​ ​ 410 ​ 519 Astellas (Japan) ​ ​ 570 ​ 504 ​ ​ 1,066 ​ 983 Co-Promotion and Other Agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Alnylam (GIVLAARI) ​ ​ 596 ​ ​ 1,061 ​ ​ 1,052 ​ ​ 2,006 Other ​ ​ 408 ​ ​ 305 ​ ​ 812 ​ ​ 659 Total collaborative arrangements revenue ​ $ 103,386 ​ $ 89,423 ​ $ 192,051 ​ $ 163,868 Sale of API ​ ​ ​ ​ ​ Linaclotide Agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AstraZeneca (China, including Hong Kong and Macau) ​ ​ 576 ​ ​ 9 ​ ​ 597 ​ ​ 5,507 Other ​ ​ 69 ​ ​ — ​ ​ 228 ​ ​ — Total sale of API ​ $ 645 ​ $ 9 ​ $ 825 ​ $ 5,507 ​ ​ ​ The Company routinely assesses the creditworthiness of its license and collaboration partners. The Company has not experienced any material losses related to receivables from its license or collaboration partners during the three and six months ended June 30, 2021 and 2020. ​ Linaclotide Agreements ​ Collaboration Agreement for North America with AbbVie ​ In September 2007, the Company entered into a collaboration agreement with AbbVie to develop and commercialize linaclotide for the treatment of IBS-C, CIC, and other GI conditions in North America. Under the terms of this collaboration agreement, the Company received a non-refundable, upfront licensing fee and shares equally with AbbVie all development costs as well as net profits or losses from the development and sale of linaclotide in the U.S. The Company receives royalties in the mid-teens percent based on net sales in Canada and Mexico. AbbVie is solely responsible for the further development, regulatory approval and commercialization of linaclotide in those countries and funding any costs. The collaboration agreement for North America also includes contingent milestone payments, as well as a contingent equity investment, based on the achievement of specific development and commercial milestones. As of June 30, 2021, $205.0 million in license fees and all six development milestone payments had been received by the Company, as well as a $25.0 million equity investment in the Company’s capital stock. The Company can also achieve up to $80.0 million in a sales-related milestone if certain conditions are met, which will be recognized as collaborative arrangements revenue when it is probable that a significant reversal of revenue would not occur, and the associated constraints have been lifted. During the three and six months ended June 30, 2021, the Company incurred $1.8 million and $3.6 million, respectively, in total research and development expenses under the linaclotide collaboration for North America. During the three and six months ended June 30, 2020, the Company incurred $6.2 million and $12.9 million, respectively, in total research and development expenses under the linaclotide collaboration for North America. As a result of the research and development cost-sharing provisions of the linaclotide collaboration for North America, the Company incurred $2.8 million and $5.7 million, in incremental research and development costs during the three and six months ended June 30, 2021, respectively, and incurred $0.5 million and $1.2 million in incremental research and development costs during the three and six months ended June 30, 2020, respectively, to reflect the obligations of each party under the collaboration to bear 50% of the development costs incurred. The Company and AbbVie began commercializing LINZESS in the U.S. in December 2012. The Company receives 50% of the net profits and bears 50% of the net losses from the commercial sale of LINZESS in the U.S. Net profits or net losses consist of net sales of LINZESS to third-party customers and sublicense income in the U.S. less the cost of goods sold as well as selling, general and administrative expenses. LINZESS net sales are calculated and recorded by AbbVie and may include gross sales net of discounts, rebates, allowances, sales taxes, freight and insurance charges, and other applicable deductions. The Company evaluated its collaboration arrangement for North America with AbbVie and concluded that all development-period performance obligations had been satisfied as of September 2012. However, the Company has determined that there are three remaining commercial-period performance obligations, which include the sales detailing of LINZESS, participation in the joint commercialization committee, and approved additional trials. The consideration remaining includes cost reimbursements in the U.S., as well as commercial sales-based milestones and net profit and loss sharing payments based on net sales in the U.S. Additionally, the Company receives royalties in the mid-teens percent based on net sales in Canada and Mexico. Royalties, commercial sales-based milestones, and net profit and loss sharing payments will be recorded as collaborative arrangements revenue or expense in the period earned, as these payments relate predominately to the license granted to AbbVie. The Company records royalty revenue in the period earned based on royalty reports from its partner, if available, or based on the projected sales and historical trends. The cost reimbursements received from AbbVie during the commercialization period will be recognized as earned in accordance with the right-to-invoice practical expedient, as the Company’s right to consideration corresponds directly with the value of the services transferred during the commercialization period. Under the Company’s collaboration agreement with AbbVie for North America, LINZESS net sales are calculated and recorded by AbbVie and include gross sales net of discounts, rebates, allowances, sales taxes, freight and insurance charges, and other applicable deductions, as noted above. These amounts include the use of estimates and judgments, which could be adjusted based on actual results in the future. The Company records its share of the net profits or net losses from the sales of LINZESS in the U.S. less commercial expenses on a net basis, and presents the settlement payments to and from AbbVie as collaboration expense or collaborative arrangements revenue, as applicable. This treatment is in accordance with the Company’s revenue recognition policy, given that the Company is not the primary obligor and does not have the inventory risks in the collaboration agreement with AbbVie for North America. The Company relies on AbbVie to provide accurate and complete information related to net sales of LINZESS in accordance with U.S. generally accepted accounting principles in order to calculate its settlement payments to and from AbbVie and record collaboration expense or collaborative arrangements revenue, as applicable. AbbVie ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2021 2020 2021 2020 Collaborative arrangements revenue related to sales of LINZESS in the U.S. ​ $ 100,307 ​ $ 86,503 ​ $ 186,256 ​ $ 157,645 Royalty revenue ​ 731 ​ 423 ​ 1,281 ​ ​ 973 Total collaborative arrangements revenue ​ $ 101,038 ​ $ 86,926 ​ $ 187,537 ​ $ 158,618 ​ The collaborative arrangements revenue recognized in the three and six months ended June 30, 2021 and 2020 primarily represents the Company’s share of the net profits and net losses on the sale of LINZESS in the U.S. ​ The Company incurred $7.5 million and $14.5 million in total selling, general and administrative costs related to the sale of LINZESS in the U.S. in accordance with the cost-sharing arrangement with AbbVie, which included an insignificant amount in patent prosecution and patent litigation costs, for each of the three and six months ended June 30, 2021, respectively. The Company incurred $4.1 million and $13.0 million in total selling, general and administrative costs related to the sale of LINZESS in the U.S. in accordance with the cost-sharing arrangement with AbbVie, which included an insignificant amount and $0.4 million in patent prosecution and patent litigation costs, for the three and six months ended June 30, 2020, respectively. ​ ® ​ License Agreement with AbbVie (All countries other than the countries and territories of North America, China (including Hong Kong and Macau), and Japan) In April 2009, the Company entered into a license agreement with Almirall, S.A. (“Almirall”) to develop and commercialize linaclotide in Europe (including the Commonwealth of Independent States and Turkey) for the treatment of IBS-C, CIC and other GI conditions (the “European License Agreement”). In accordance with the European License Agreement, the Company granted Almirall a right to access its U.S. Phase III clinical trial data for the purposes of supporting European regulatory approval. In October 2015, Almirall transferred its exclusive license to develop and commercialize linaclotide in Europe to AbbVie. Additionally, in October 2015, the Company and AbbVie separately entered into an amendment to the European License Agreement relating to the development and commercialization of linaclotide in Europe. Pursuant to the terms of the amendment, (i) certain sales-based milestones payable to the Company under the European License Agreement were modified to increase the total milestone payments such that, when aggregated with certain commercial launch milestones, they could total up to $42.5 million, (ii) the royalties payable to the Company during the term of the European License Agreement were modified such that the royalties based on sales volume in Europe begin in the mid-single digit percent and escalate to the upper-teens percent by calendar year 2019, and (iii) AbbVie assumed responsibility for the manufacturing of linaclotide API for Europe from the Company, as well as the associated costs. The Company concluded that the 2015 amendment to the European License Agreement was not a modification to the linaclotide collaboration agreement with AbbVie for North America. In January 2017, the Company and AbbVie entered into an amendment to the European License Agreement (the “2017 Amendment”). The 2017 Amendment extended the license to develop and commercialize linaclotide in all countries other than China (including Hong Kong and Macau), Japan, and the countries and territories of North America. On a country-by-country and product-by-product basis in such additional territory, AbbVie is obligated to pay the Company a royalty as a percentage of net sales of products containing linaclotide as an active ingredient in the upper-single digits for five years following the first commercial sale of a linaclotide product in a country, and in the low-double digits thereafter. The royalty rate for products in the expanded territory will decrease, on a country-by-country basis, to the lower-single digits, or cease entirely, following the occurrence of certain events. The 2017 Amendment did not modify any of the milestones or royalty terms related to Europe. In evaluating the terms of the European License Agreement, as amended by the 2017 Amendment (the “Amended European License Agreement”), the Company determined that there are no remaining performance obligations as of September 2012. However, the Company continues to be eligible to receive consideration in the form of commercial launch milestones, sales-based milestones, and royalties. The commercial launch milestones, sales-based milestones and royalties under the Amended European License Agreement relate predominantly to the license granted to AbbVie. The Company records royalties on sales of CONSTELLA in Europe in the period earned based on royalty reports from its partner, if available, or the projected sales and historical trends under the sales-based royalty exception. The commercial launch milestones are recognized as revenue when it is probable that a significant reversal of revenue would not occur and the associated constraint has been lifted. The Company recognized $0.6 million and $1.2 million of royalty revenue from the Amended European License Agreement during the three and six months ended June 30, 2021, respectively. The Company recognized $0.4 million and $1.1 million of royalty revenue from the Amended European License Agreement during the three and six months ended June 30, 2020, respectively. License Agreement for Japan with Astellas In November 2009, the Company entered into a license agreement with Astellas, as amended, to develop and commercialize linaclotide for the treatment of IBS-C, CIC and other GI conditions in Japan (the “2009 License Agreement with Astellas”). Astellas is responsible for all activities relating to development, regulatory approval and commercialization in Japan as well as funding the associated costs and the Company was required to participate on a joint development committee over linaclotide’s development period. Under the 2009 License Agreement with Astellas, the Company received an upfront licensing fee of $30.0 million and three development milestone payments that totaled $45.0 million and has no remaining performance obligations. In April 2017, the Company and Astellas entered into a commercial API supply agreement (the “Astellas Commercial Supply Agreement”). Pursuant to the Astellas Commercial Supply Agreement, the Company sold linaclotide API supply to Astellas at a contractually defined rate and recognized related revenue as sale of API. Under the 2009 License Agreement with Astellas, the Company received royalties which escalated based on sales volume, beginning in the low-twenties percent, less the transfer price paid for the API included in the product sold and other contractual deductions. In August 2019, the Company and Astellas amended and restated the 2009 License Agreement with Astellas (the “Amended Astellas License Agreement”). This amendment to the 2009 License Agreement with Astellas was accounted for as a separate contract. Under the terms of the Amended Astellas License Agreement, the Company is no longer responsible for the supply of linaclotide API to Astellas, and Astellas assumed responsibility for its own supply of linaclotide API in Japan in 2020, other than minimal quantities of API the Company supplied to Astellas in 2020 relating to orders for linaclotide API placed by Astellas in 2019. ​ In connection with the execution of the Amended Astellas License Agreement, Astellas paid the Company a non-refundable, upfront payment of $10.0 million in August 2019. Further, Astellas, in lieu of the royalty payment terms set forth in the 2009 License Agreement with Astellas, is required to pay royalties to the Company at rates beginning in the mid-single digit percent and escalating to low-double-digit percent, based on aggregate annual net sales in Japan of products containing linaclotide API. These royalty payments are subject to reduction following the expiration of certain licensed patents and the occurrence of generic competition in Japan. The Company continued to supply linaclotide API for Japan during 2019 and 2020 at a contractually defined rate. Additionally, Astellas reimbursed the Company for the Company’s performance of adverse event reporting services at a fixed monthly rate until such services were terminated in February 2020. ​ The Company identified the following performance obligations under the Amended Astellas License Agreement: ● delivery of the expanded license of intellectual property, including the applicable manufacturing know-how; ● obligation to supply linaclotide API for 2019; and ● adverse event reporting services. ​ The Company allocated the $10.0 million upfront payment to the delivery of the expanded license of intellectual property and recognized it as collaborative arrangements revenue at contract inception. The Company allocated the $20.4 million in remaining purchase orders for API to the obligation to supply linaclotide API to Astellas for 2019. Consideration for the supply of linaclotide API was recognized over the performance period as linaclotide API is shipped to Astellas. Consideration allocated to the adverse event reporting services was recognized as such services were provided over the performance period based on the amount to which the Company has a right to invoice. ​ Royalties on sales of LINZESS in Japan relate predominantly to the license granted to Astellas. Accordingly, the Company applies the sales-based royalty exception and records royalties on sales of LINZESS in Japan in the period earned based on royalty reports from its partner, if available, or the projected sales and historical trends. ​ The Company recognized $0.6 million and $1.1 million of royalty revenue during the three and six months ended June 30, 2021, respectively, under the Amended Astellas License Agreement. The Company recognized $0.5 million and $1.0 million in collaborative arrangements revenue during the three and six months ended June 30, 2020, respectively, under the Amended Astellas License Agreement, of which $0.5 million and $0.9 million related to royalties, respectively. ​ Collaboration Agreement for China (including Hong Kong and Macau) with AstraZeneca In October 2012, the Company entered into a collaboration agreement with AstraZeneca to co-develop and co-commercialize linaclotide in the AstraZeneca License Territory (the “AstraZeneca Collaboration Agreement”). The collaboration provided AstraZeneca with an exclusive nontransferable license to exploit the underlying technology in the AstraZeneca License Territory. The parties shared responsibility for continued development and commercialization of linaclotide under a joint development plan and a joint commercialization plan, respectively, with AstraZeneca having primary responsibility for the local operational execution. In September 2019, the Company and AstraZeneca entered into an amendment and restatement of the AstraZeneca Collaboration Agreement (the “Amended AstraZeneca Agreement”) under which AstraZeneca obtained the exclusive right to develop, manufacture and commercialize products containing linaclotide in the AstraZeneca License Territory (the “AstraZeneca License”). Under the Amended AstraZeneca Agreement, the Company is entitled to receive non-contingent payments totaling $35.0 million in three installments through 2024, of which $10.0 million was received in January 2021. In addition, AstraZeneca may be required to make milestone payments totaling up to $90.0 million contingent on the achievement of certain sales targets and will be required to pay tiered royalties to the Company at rates beginning in the mid-single-digit percent and increasing up to twenty percent based on the aggregate annual net sales of products containing linaclotide in the AstraZeneca License Territory. In connection with the Amended AstraZeneca Agreement, the Company and AstraZeneca entered into a transition services agreement (“AstraZeneca TSA”) and an amended commercial supply agreement (“AstraZeneca CSA”). Under the terms of the AstraZeneca TSA, the Company will provide certain regulatory and administrative services for a term of approximately two years from the date of execution, unless earlier terminated or extended. Services performed are paid at a mutually agreed upon rate. Amounts for AstraZeneca TSA services are recorded as collaborative arrangements revenue. Under the terms of the AstraZeneca CSA, the Company supplied linaclotide API, finished drug product and finished goods for the Licensed Territory through March 31, 2020 at predetermined rates. The Company evaluated the Amended AstraZeneca Agreement and determined that it would be accounted for as a separate contract because it adds a distinct good or service at an amount that reflects standalone selling price. The following performance obligations under the Amended AstraZeneca Agreement were identified: ● delivery of the expanded AstraZeneca License; ● AstraZeneca TSA services; and ● supply of linaclotide API, finished drug product and finished goods under the AstraZeneca CSA. The Company determined that the non-contingent payments should be allocated to the delivery of the expanded AstraZeneca License. The Company determined that the performance obligation related to the transfer of the AstraZeneca License was satisfied as of the execution date of the Amended AstraZeneca Agreement. As a portion of the payments relating to the transfer of the AstraZeneca License are due significantly after the performance obligation was satisfied, the Company adjusted its transaction price for the significant financing component of $2.6 million. Accordingly, the Company recognized $32.4 million in 2019 relating to the delivery of the AstraZeneca License as collaborative arrangements revenue at contract inception and is recognizing the $2.6 million relating to the significant financing component as interest income through 2024 using the effective interest method. Consideration allocated to the AstraZeneca TSA services will be recognized as collaborative arrangements revenue as such services are provided over the performance period based on the amount to which the Company has a right to invoice. Consideration for the supply of linaclotide API, finished drug product and finished goods under the AstraZeneca CSA was recognized over the performance period as linaclotide API, finished drug product and finished goods were shipped to AstraZeneca. During the three and six months ended June 30, 2021, the Company recognized an insignificant amount and $0.2 million, respectively, in collaborative arrangements revenue under the Amended AstraZeneca Agreement related to AstraZeneca TSA services. During the three and six months ended June 30, 2021, the Company recognized an insignificant amount and $0.2 million, respectively, in collaborative arrangements revenue under the Amended AstraZeneca Agreement related to royalties. Additionally, the Company recognized $0.6 million, in sales of API relating to the supply of reference standard material to AstraZeneca during each of the three and six months ended June 30, 2021. T he Company recognized an insignificant amount and $0.3 million, respectively, in interest income related to the significant financing component of the Amended AstraZeneca Agreement during the three and six months ended June 30, 2021, respectively. ​ During the three and six months ended June 30, 2020, the Company recognized $0.2 million and $0.4 million, respectively, in collaborative arrangements revenue under the Amended AstraZeneca Agreement related to AstraZeneca TSA services. During the three and six months ended June 30, 2020, the Company recognized an insignificant amount and $0.2 million, respectively, in collaborative arrangements revenue under the Amended AstraZeneca Agreement related to royalties. Additionally, the Company recognized an insignificant amount and $5.5 million, in sales of API relating to the supply of linaclotide finished drug product and finished goods under the AstraZeneca CSA during the three and six months ended June 30, 2020, respectively. T he Company recognized $0.2 million and $0.4 million, respectively, in interest income related to the significant financing component of the Amended AstraZeneca Agreement during the three and six months ended June 30, 2020. ​ Co-promotion and Other Agreements ​ Disease Education and Promotional Agreement with Alnylam ​ In August 2019, the Company and Alnylam entered into a disease education and promotional agreement for Alnylam’s GIVLAARI, and this agreement was subsequently amended in December 2020 (the “Alnylam Agreement”). GIVLAARI was approved by the U.S. FDA in November 2019 for the treatment of adult patients with AHP. Under the terms of the Alnylam Agreement, the Company’s sales force is performing disease awareness activities and sales detailing activities for GIVLAARI to gastroenterologists and health care practitioners to whom they detail LINZESS in the first position over the term of the agreement, which is approximately three years. In June 2021, the Alnylam Agreement was terminated with an effective termination date of September 30, 2021. Under the Alnylam Agreement, the Company received service fees, totaling $5.5 million for services rendered through December 31, 2020. In connection with the amendment of the Alnylam Agreement, beginning in 2021, the Company no longer receives service fees. The Company is eligible to receive royalties based on a percentage of net sales of GIVLAARI that are directly attributable to the Company’s promotional efforts over the term of the agreement. The Company identified the following performance obligation under the Alnylam Agreement: ● performance of disease education activities for AHP and performance of sales details for GIVLAARI (together “Givosiran Education and Promotion Activities”). The Company allocated the service fees to the performance of Givosiran Education and Promotion Activities and recognized collaborative arrangements revenue through December 31, 2020 as the services were performed based on the amount to which the Company had a right to invoice. Royalties are recognized as collaborative arrangements revenue for Givosiran Education and Promotion Activities based on the amount to which the Company has a right to invoice when the associated constraints have been lifted. During the three and six months ended June 30, 2021, the Company recognized $0.6 million and $1.1 million, respectively, in royalty revenue under the Alnylam Agreement. During the three and six months ended June 30, 2020, the Company recognized $1.1 million and $2.0 million, respectively, in collaborative arrangements revenue, of which $0.9 million and $1.8 million, respectively, related to the service fees and $0.2 million in each period related to royalties.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Fair Value of Financial Instruments	5. Fair Value of Financial Instruments ​ The tables below present information about the Company’s assets that are measured at fair value on a recurring basis as of June 30, 2021 and December 31, 2020 and indicate the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize observable inputs such as quoted prices in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize data points that are either directly or indirectly observable, such as quoted prices for similar instruments in active markets, interest rates and yield curves. Fair values determined by Level 3 inputs utilize unobservable data points in which there is little or no market data, which require the Company to develop its own assumptions for the asset or liability. The Company’s investment portfolio may include fixed income securities that do not always trade on a daily basis. As a result, the pricing services used by the Company apply other available information as applicable through processes such as benchmark yields, benchmarking of like securities, sector groupings and matrix pricing to prepare valuations. In addition, model processes are used to assess interest rate impact and develop prepayment scenarios. These models take into consideration relevant credit information, perceived market movements, sector news and economic events. The inputs into these models may include benchmark yields, reported trades, broker-dealer quotes, issuer spreads and other relevant data. The Company validates the prices provided by its third-party pricing services by obtaining market values from other pricing sources and analyzing pricing data in certain instances. The Company periodically invests in certain reverse repurchase agreements, which are collateralized by Government Securities and Obligations for an amount not less than 102% of their principal amount. The Company does not record an asset or liability for the collateral as the Company is not permitted to sell or re-pledge the collateral. The collateral has at least the prevailing credit rating of U.S. Government Treasuries and Agencies. The Company utilizes a third-party custodian to manage the exchange of funds and ensure the collateral received is maintained at 102% of the reverse repurchase agreements principal amount on a daily basis. The following tables present the assets and liabilities the Company has measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using ​ ​ ​ Quoted Prices in Significant Other Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ June 30, 2021 ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 476,684 ​ ​ $ 476,684 ​ ​ — ​ ​ — Restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ ​ 2,220 ​ ​ ​ 2,220 ​ ​ — ​ ​ — Convertible note hedges ​ ​ 11,262 ​ ​ ​ — ​ ​ — ​ ​ 11,262 Total assets measured at fair value ​ $ 490,166 ​ ​ $ 478,904 ​ $ — ​ $ 11,262 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Note hedge warrants ​ $ 11,061 ​ ​ $ — ​ ​ — ​ ​ 11,061 Total liabilities measured at fair value ​ $ 11,061 ​ ​ $ — ​ $ — ​ $ 11,061 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using ​ ​ ​ Quoted Prices in Significant Other Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ December 31, 2020 ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 349,014 ​ ​ $ 349,014 ​ $ — ​ $ — Restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ 2,221 ​ ​ 2,221 ​ — ​ — Convertible note hedges ​ ​ 13,065 ​ ​ ​ — ​ ​ — ​ ​ 13,065 Total assets measured at fair value ​ $ 364,300 ​ ​ $ 351,235 ​ $ — ​ $ 13,065 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Note hedge warrants ​ $ 12,088 ​ ​ $ — ​ $ — ​ $ 12,088 Total liabilities measured at fair value ​ $ 12,088 ​ ​ $ — ​ $ — ​ $ 12,088 ​ There were no transfers between fair value measurement levels during each of the three and six months ended June 30, 2021 or 2020. ​ Cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable, accrued research and development costs, accrued expenses and other current liabilities and current portion of operating lease obligations at June 30, 2021 and December 31, 2020 are carried at amounts that approximate fair value due to their short-term maturities. ​ Convertible Note Hedges and Note Hedge Warrants with Respect to 2022 Convertible Notes ​ The Company’s Convertible Note Hedges and the Note Hedge Warrants are recorded as derivative assets and liabilities, respectively, and are classified as Level 3 measurements under the fair value hierarchy. These derivatives are not actively traded and are valued using the Black-Scholes option-pricing model, which requires the use of subjective assumptions. Significant inputs used to determine the fair value as of June 30, 2021 included the price per share of the Company’s Class A Common Stock, expected terms of the derivative instruments, strike prices of the derivative instruments, risk-free interest rates, and expected volatility of the Company’s Class A Common Stock. Changes to these inputs could materially affect the valuation of the Convertible Note Hedges and Note Hedge Warrants. The following inputs were used in the fair market valuation of the Convertible Note Hedges and Note Hedge Warrants as of June 30, 2021 and December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six Months Ended ​ Year Ended ​ ​ ​ June 30, 2021 ​ December 31, 2020 ​ ​ ​ Convertible Note Hedge ​ Convertible Note Hedge ​ ​ Note Hedges ​ Warrants Note Hedges ​ Warrants Risk-free interest rate (1) ​ ​ 0.1 % ​ 0.2 % ​ 0.1 % ​ 0.1 % Expected term ​ 1.0 ​ 1.5 ​ ​ 1.5 ​ 2.0 ​ Stock price (2) ​ $ 12.87 ​ $ 12.87 ​ $ 11.39 ​ $ 11.39 ​ Strike price (3) ​ $ 14.51 ​ $ 18.82 ​ $ 14.51 ​ $ 18.82 ​ Common stock volatility (4) ​ ​ 39.0 % ​ 46.1 % ​ 46.7 % ​ 50.3 % Dividend yield (5) ​ — % — % — % — % (1) Based on U.S. Treasury yield curve, with terms commensurate with the expected terms of the Convertible Note Hedges and the Note Hedge Warrants. (2) The closing price of the Company’s Class A Common Stock on the last trading days of the quarters ended June 30, 2021 and December 31, 2020, respectively. (3) As per the respective agreements for the Convertible Note Hedges and Note Hedge Warrants. (4) Expected volatility based on historical volatility of the Company’s Class A Common Stock. (5) The Company has not paid and does not anticipate paying cash dividends on its shares of common stock in the foreseeable future; therefore, the expected dividend yield is assumed to be zero. ​ The Convertible Note Hedges and the Note Hedge Warrants are recorded at fair value at each reporting date and changes in fair value are recorded in other (expense) income, net within the Company’s condensed consolidated statements of income. ​ The following table reflects the change in the Company’s Level 3 Convertible Note Hedges and Note Hedge Warrants from December 31, 2020 through June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible ​ Note Hedge ​ Note Hedges Warrants Balance at December 31, 2020 ​ $ 13,065 ​ $ (12,088) Change in fair value, recorded as a component of (loss) gain on derivatives ​ ​ (1,803) ​ ​ 1,027 Balance at June 30, 2021 ​ $ 11,262 ​ $ (11,061) ​ Convertible Senior Notes ​ In June 2015, the Company issued $335.7 million aggregate principal amount of its 2022 Convertible Notes. In August 2019, the Company issued $200.0 million aggregate principal amount of its 2024 Convertible Notes and $200.0 million aggregate principal amount of its 2026 Convertible Notes, and used a portion of the proceeds from such issuances to repurchase $215.0 million aggregate principal amount of its 2022 Convertible Notes. The Company separately accounted for the liability and equity components of each of the 2022 Convertible Notes, 2024 Convertible Notes, and 2026 Convertible Notes, by allocating the proceeds between the liability component and equity component (Note 8). The fair value of the respective convertible senior notes, which differs from their carrying value, is influenced by interest rates, the price of the Company’s Class A Common Stock and the volatility thereof, and the prices for the respective convertible senior notes observed in market trading, which are Level 2 inputs. ​ The estimated fair value of the 2022 Convertible Notes was $131.1 million and $130.2 million as of June 30, 2021 and December 31, 2020, respectively. The estimated fair value of the 2024 Convertible Notes was $234.7 million and $222.3 million as of June 30, 2021 and December 31, 2020, respectively. The estimated fair value of the 2026 Convertible Notes was $239.2 million and $224.1 million as of June 30, 2021 and December 31, 2020, respectively. ​ Capped Calls with Respect to 2024 Convertible Notes and 2026 Convertible Notes ​ Derivatives and Hedging ​

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Accrued Expenses and Other Current Liabilities	6. Accrued Expenses and Other Current Liabilities ​ Accrued expenses and other current liabilities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 December 31, 2020 Accrued incentive compensation ​ $ 6,879 ​ $ 8,719 Accrued vacation ​ ​ 2,400 ​ ​ 2,625 Professional fees ​ 1,283 ​ 530 Salaries ​ ​ 972 ​ ​ 627 Other employee benefits ​ ​ 438 ​ ​ 1,442 Restructuring liabilities ​ ​ 2,124 ​ ​ 10,510 Other ​ 2,157 ​ 2,033 Total accrued expenses and other current liabilities ​ $ 16,253 ​ $ 26,486 ​ ​ ​ ​ As of June 30, 2021, other accrued expenses of $2.2 million included $1.5 million of uninvoiced vendor liabilities and $0.3 million of accrued interest expense. As of December 31, 2020, other accrued expenses of $2.0 million included $1.6 million of uninvoiced vendor liabilities and $0.3 million of accrued interest. ​

Leases

Leases	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Leases	7. Leases ​ The Company’s lease portfolio for the three and six months ended June 30, 2021 includes: an office lease for its current headquarters location, a data center colocation lease, vehicle leases for its salesforce representatives, and leases for computer and office equipment. ​ The Company’s office lease and vehicle lease require letters of credit to secure the Company’s obligations under the lease agreements totaling $2.2 million and are collateralized by money market accounts recorded as restricted cash on the Company’s condensed consolidated balance sheets as of June 30, 2021 and December 31, 2020. ​ Lease cost is recognized on a straight-line basis over the lease term. The components of lease cost for the three and six months ended June 30, 2021 and 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ ​ June 30, ​ June 30, ​ ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 ​ Operating lease cost ​ $ 630 ​ $ 633 ​ $ 1,261 ​ $ 1,266 ​ Short-term lease cost ​ ​ 214 ​ ​ 360 ​ ​ 428 ​ ​ 732 ​ Total lease cost ​ $ 844 ​ $ 993 ​ $ 1,689 ​ $ 1,998 ​ ​ Supplemental information related to leases for the periods reported is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six Months Ended June 30, ​ ​ ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities (in thousands) ​ ​ $ 778 ​ ​ $ 86 ​ Weighted-average remaining lease term of operating leases (in years) ​ ​ ​ 8.8 ​ ​ ​ 9.7 ​ Weighted-average discount rate of operating leases ​ ​ ​ 5.8 % ​ ​ 5.8 % ​ Future minimum lease payments under non-cancelable operating leases as of June 30, 2021 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ Operating ​ Lease ​ ​ Payments 2021 (1) ​ $ 1,578 2022 ​ ​ 3,129 2023 ​ ​ 3,065 2024 ​ ​ 3,126 2025 ​ 3,189 2026 and thereafter ​ 14,855 Total future minimum lease payments ​ ​ 28,942 Less: present value adjustment ​ ​ (6,387) Operating lease liabilities at June 30, 2021 ​ ​ 22,555 Less: current portion of operating lease liabilities ​ ​ (3,161) Operating lease liabilities, net of current portion ​ $ 19,394 (1) For the six months ending December 31, 2021. ​ Summer Street Lease ​ In June 2019, the Company entered into a non-cancelable operating lease (the “Summer Street Lease”) for approximately 39,000 square feet of office space on the 23 rd ​ At lease inception, the Company recorded a right-of-use asset and a lease liability using an incremental borrowing rate of 5.8%. At June 30, 2021, the balances of the right-of-use asset and operating lease liability were $16.0 million and $22.3 million, respectively. At December 31, 2020, the balances of the right-of-use asset and operating lease liability were $16.6 million and $23.2 million, respectively. ​ Lease costs recorded during the three and six months ended June 30, 2021 were $0.6 million and $1.3 million, respectively. Lease costs recorded during the three and six months ended June 30, 2020 were $0.7 million and $1.3 million, respectively.

Notes Payable

Notes Payable	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Notes Payable	8. Notes Payable 2.25% Convertible Senior Notes due 2022 In June 2015, the Company issued $335.7 million aggregate principal amount of the 2022 Convertible Notes. The Company received net proceeds of $324.0 million from the sale of the 2022 Convertible Notes, after deducting fees and expenses of $11.7 million. The Company used $21.1 million of the net proceeds from the sale of the 2022 Convertible Notes to pay the net cost of the Convertible Note Hedges (after such cost was partially offset by the proceeds to the Company from the sale of the Note Hedge Warrants), as described below. The 2022 Convertible Notes are governed by an indenture (the “2022 Indenture”) between the Company and U.S. Bank National Association, as trustee (the “Trustee”). The 2022 Convertible Notes are senior unsecured obligations and bear cash interest at the annual rate of 2.25%, payable on June 15 and December 15 of each year. The 2022 Convertible Notes will mature on June 15, 2022, unless earlier converted or repurchased. The Company may settle conversions of the 2022 Convertible Notes through payment or delivery, as the case may be, of cash, shares of the Company’s Class A Common Stock or a combination of cash and shares of Class A Common Stock, at the Company’s option (subject to, and in accordance with, the settlement provisions of the 2022 Indenture). The initial conversion rate for the 2022 Convertible Notes was 60.3209 shares of Class A Common Stock (subject to adjustment as provided for in the 2022 Indenture) per $1,000 principal amount of the 2022 Convertible Notes, which was equal to an initial conversion price of $16.58 per share and 20,249,665 shares. In connection with the Separation, in April 2019, the conversion rate under the 2022 Indenture was adjusted to equal 68.9172 shares of Class A Common Stock per $1,000 principal amount of the 2022 Convertible Notes, which is equal to an adjusted conversion price of $14.51 per share and 23,135,435 shares. ​ Holders of the 2022 Convertible Notes may convert their 2022 Convertible Notes at their option at any time prior to the close of business on the business day immediately preceding December 15, 2021 in multiples of $1,000 principal amount, only under the following circumstances: ● during any calendar quarter commencing after the calendar quarter ending on September 30, 2015 (and only during such calendar quarter), if the last reported sale price of the Company’s Class A Common Stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the 2022 Convertible Notes on each applicable trading day; ● during the five business day period after any five consecutive trading day period (the “measurement period”) in which the “trading price” (as defined in the 2022 Indenture) per $1,000 principal amount of the 2022 Convertible Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s Class A Common Stock and the conversion rate for the 2022 Convertible Notes on each such trading day; or ● upon the occurrence of specified corporate events described in the 2022 Indenture. On or after December 15, 2021, until the close of business on the second scheduled trading day immediately preceding June 15, 2022, holders may convert their 2022 Convertible Notes, in multiples of $1,000 principal amount, at the option of the holder regardless of the foregoing circumstances. Upon the occurrence of certain fundamental changes, as described in the 2022 Indenture, holders of the 2022 Convertible Notes may require the Company to repurchase for cash all or part of their 2022 Convertible Notes at a repurchase price equal to 100% of the principal amount of the 2022 Convertible Notes to be repurchased, plus accrued and unpaid interest. If a make-whole fundamental change, as described in the 2022 Indenture, occurs and a holder elects to convert its 2022 Convertible Notes in connection with such make-whole fundamental change, such holder may be entitled to an increase in the conversion rate as described in the 2022 Indenture. The 2022 Indenture does not contain any financial covenants or restrict the Company’s ability to repurchase the Company’s securities, pay dividends or make restricted payments in the event of a transaction that substantially increases the Company’s level of indebtedness. The 2022 Indenture provides for customary events of default. In the case of an event of default with respect to the 2022 Convertible Notes arising from specified events of bankruptcy or insolvency, all outstanding 2022 Convertible Notes will become due and payable immediately without further action or notice. If any other event of default with respect to the 2022 Convertible Notes under the 2022 Indenture occurs or is continuing, the Trustee or holders of at least 25% in aggregate principal amount of the then outstanding 2022 Convertible Notes may declare the principal amount of the 2022 Convertible Notes to be immediately due and payable. Notwithstanding the foregoing, the 2022 Indenture provides that, upon the Company’s election, and for up to 180 days, the sole remedy for an event of default relating to certain failures by the Company to comply with certain reporting covenants in the 2022 Indenture consists exclusively of the right to receive additional interest on the 2022 Convertible Notes. In accordance with accounting guidance for debt with conversion and other options, the Company separately accounted for the liability and equity components of the 2022 Convertible Notes by allocating the proceeds between the liability component and the embedded conversion option, or equity component, due to the Company's ability to settle the 2022 Convertible Notes in cash, its Class A Common Stock, or a combination of cash and Class A Common Stock at the option of the Company. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated conversion feature. The equity component of the 2022 Convertible Notes was recognized as a debt discount and represents the difference between the gross proceeds from the issuance of the 2022 Convertible Notes and the fair value of the liability component of the 2022 Convertible Notes on their respective dates of issuance. The debt discount is amortized to interest expense using the effective interest method over seven years, or the expected life of the 2022 Convertible Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. ​ In connection with the issuance of the 2024 Convertible Notes and the 2026 Convertible Notes in August 2019, the Company repurchased $215.0 million aggregate principal amount of the 2022 Convertible Notes. The 2022 Convertible Notes were repurchased at a premium totaling $227.3 million. The Company recognized a loss on extinguishment of debt of $23.4 million during the year ended December 31, 2019 related to the prepayment premium and proportional write-off of the 2022 Convertible Notes unamortized debt issuance costs and unamortized debt discount. Additionally, the repurchase resulted in a reduction to additional paid-in capital of $27.0 million during the year ended December 31, 2019 related to the equity component of the 2022 Convertible Notes. ​ 0.75% Convertible Senior Notes due 2024 and 1.50% Convertible Senior Notes due 2026 ​ In August 2019, the Company issued $200.0 million aggregate principal amount of the 2024 Convertible Notes and $200.0 million aggregate principal amount of the 2026 Convertible Notes. The Company received net proceeds of $391.0 million from the sale of the 2024 Convertible Notes and 2026 Convertible Notes, after deducting fees and expenses of $9.0 million. The Company used $25.2 million of the net proceeds from the sale of the 2024 Convertible Notes and 2026 Convertible Notes to pay the cost of the Capped Calls, as described below. For purposes of this section, “Notes” refer to the 2024 Convertible Notes and the 2026 Convertible Notes, collectively. ​ The 2024 Convertible Notes and 2026 Convertible Notes were issued by the Company on August 12, 2019, pursuant to separate Indentures, each dated as of such date (each an “Indenture” and together the “Indentures”), between the Company and the Trustee. The 2024 Convertible Notes bear cash interest at the annual rate of 0.75% and the 2026 Convertible Notes bear cash interest at the annual rate of 1.50%, each payable on June 15 and December 15 of each year. The 2024 Convertible Notes will mature on June 15, 2024 and the 2026 Convertible Notes will mature on June 15, 2026, unless earlier converted or repurchased. The Company will settle conversions of the 2024 Convertible Notes and 2026 Convertible Notes through payment or delivery, as the case may be, of cash, shares of the Company’s Class A Common Stock or a combination of cash and shares of Class A Common Stock, at the Company’s option (subject to, and in accordance with, the settlement provisions of the applicable Indenture). The initial conversion rate for each of the 2024 Convertible Notes and the 2026 Convertible Notes is 74.6687 shares of Class A Common Stock (subject to adjustment as provided for in the applicable Indenture) per $1,000 principal amount of the 2024 Convertible Notes and 2026 Convertible Notes, which is equal to an initial conversion price of $13.39 per share. ​ Holders of the 2024 Convertible Notes and 2026 Convertible Notes may convert their Notes at their option at any time prior to the close of business on the business day immediately preceding December 15, 2023, with respect to the 2024 Convertible Notes, and December 15, 2025, with respect to the 2026 Convertible Notes, in multiples of $1,000 principal amount, only under the following circumstances: ​ ● during any calendar quarter commencing after the calendar quarter ending on December 31, 2019 (and only during such calendar quarter), if the last reported sale price of Class A Common Stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price for the Notes on each applicable trading day; ​ ● during the five- business day period after any five consecutive trading day period (the “measurement period”) in which the “trading price” (as defined in each Indenture) per $1,000 principal amount of Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of Class A Common Stock and the conversion rate for the Notes on each such trading day; or ​ ● upon the occurrence of specified corporate events described in each Indenture. ​ On or after December 15, 2023, with respect to the 2024 Convertible Notes, and December 15, 2025, with respect to the 2026 Convertible Notes, until the close of business on the second scheduled trading day immediately preceding the applicable maturity date, the holders of the Notes may convert their Notes, in multiples of $1,000 principal amount, regardless of the foregoing conditions. ​ Upon the occurrence of fundamental changes, as described in the Indentures, prior to the maturity date of the respective Notes, holders of such Notes may require the Company to repurchase for cash all or a portion of their Notes at a repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest. If a make-whole fundamental change, as described in the Indentures, occurs and a holder elects to convert its Notes in connection with such make-whole fundamental change, such holder may be entitled to an increase in the conversion rate as described in the Indentures. ​ The Indentures do not contain any financial covenants or restrict the Company’s ability to repurchase the Company’s securities, pay dividends or make restricted payments in the event of a transaction that substantially increases the Company’s level of indebtedness. The Indentures provide for customary events of default. In the case of an event of default with respect to a series of Notes arising from specified events of bankruptcy or insolvency, all outstanding Notes of such series will become due and payable immediately without further action or notice. If any other event of default with respect to a series of Notes under the relevant Indenture occurs or is continuing, the Trustee or holders of at least 25% in aggregate principal amount of the then outstanding Notes of such series may declare the principal amount of such Notes to be immediately due and payable. ​ In accordance with accounting guidance for debt with conversion and other options, the Company separately accounted for the liability and equity components of the 2024 Convertible Notes and the 2026 Convertible Notes by allocating the proceeds between the liability components and the embedded conversion options, or equity components, due to the Company’s ability to settle the 2024 Convertible Notes and the 2026 Convertible Notes in cash, its Class A Common Stock, or a combination of cash and Class A Common Stock at the option of the Company. The carrying amount of the respective liability components were calculated by measuring the fair value of a similar liability that does not have an associated conversion feature. The respective equity components of the 2024 Convertible Notes and the 2026 Convertible Notes were recognized as a debt discount and represent the difference between the gross proceeds from the issuance of the 2024 Convertible Notes and 2026 Convertible Notes and the fair value of the liability of the 2024 Convertible Notes and 2026 Convertible Notes on their respective dates of issuance. The debt discount is amortized to interest expense using the effective interest method over approximately five ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 ​ December 31, 2020 ​ ​ ​ ​ ​ ​ ​ Liability component: ​ ​ ​ ​ ​ ​ Principal: ​ ​ ​ ​ ​ ​ 2022 Convertible Notes ​ $ 120,699 ​ $ 120,699 2024 Convertible Notes ​ ​ 200,000 ​ ​ 200,000 2026 Convertible Notes ​ ​ 200,000 ​ ​ 200,000 Less: unamortized debt discount ​ ​ (72,959) ​ ​ (83,900) Less: unamortized debt issuance costs ​ ​ (5,733) ​ ​ (6,543) Net carrying amount ​ $ 442,007 ​ $ 430,256 Equity component: ​ ​ ​ ​ ​ ​ 2022 Convertible Notes ​ ​ 19,807 ​ ​ 19,807 2024 Convertible Notes ​ ​ 41,152 ​ ​ 41,152 2026 Convertible Notes ​ ​ 51,350 ​ ​ 51,350 Total equity component ​ $ 112,309 ​ $ 112,309 ​ In connection with the issuance of the 2022 Convertible Notes, the Company incurred $11.7 million of debt issuance costs, which primarily consisted of initial purchasers’ discounts and legal and other professional fees. The Company allocated these costs to the liability and equity components based on the allocation of the proceeds. The portion of these costs allocated to the equity components totaling $4.0 million were recorded as a reduction to additional paid-in capital upon issuance. The portion of these costs allocated to the liability components totaling $7.7 million were recorded as a reduction in the carrying value of the debt on the consolidated balance sheet and are amortized to interest expense using the effective interest method over the expected life of the 2022 Convertible Notes. In connection with the partial repurchase of the 2022 Convertible Notes, the Company recorded a loss on extinguishment of debt of $23.4 million, of which $2.8 million related to the initial debt issuance costs, during the year ended December 31, 2019. The Company determined the expected life of the 2022 Convertible Notes was equal to their seven-year term. The effective interest rate on the liability components of the 2022 Convertible Notes for the period from the date of issuance through June 30, 2019 was 9.34%. From the date of the partial repurchase of the 2022 Convertible Notes in August 2019 through June 30, 2021, the effective interest rate on the liability component of the 2022 Convertible Notes was 9.9%. In connection with the issuance of the 2024 Convertible Notes and the 2026 Convertible Notes, the Company incurred $9.0 million of debt issuance costs, which primarily consisted of initial purchaser’s discounts and legal and other professional fees. The Company allocated these costs to the liability and equity components based on the allocation of the proceeds. The portion of these costs allocated to the equity components totaling $2.1 million were recorded as a reduction to additional paid-in capital. The portion of these costs allocated to the liability components totaling $6.9 million were recorded as a reduction in the carrying value of the debt on the consolidated balance sheet and are amortized to interest expense using the effective interest method over the expected lives of the 2024 Convertible Notes and the 2026 Convertible Notes. ​ The Company determined the expected life of the 2024 Convertible Notes and the 2026 Convertible Notes was equal to their approximately five ​ ​ The following table sets forth total interest expense recognized related to convertible senior notes during the three and six months ended June 30, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2021 2020 2021 2020 Contractual interest expense ​ $ 1,804 ​ $ 1,802 ​ $ 3,607 ​ $ 3,609 Amortization of debt issuance costs ​ ​ 412 ​ ​ 360 ​ ​ 811 ​ ​ 705 Amortization of debt discount ​ ​ 5,516 ​ ​ 5,156 ​ ​ 10,940 ​ ​ 10,224 Total interest expense ​ $ 7,732 ​ $ 7,318 ​ $ 15,358 ​ $ 14,538 ​ Future minimum payments under the convertible senior notes as of June 30, 2021, are as follows (in thousands): ​ ​ ​ ​ 2021 (1) ​ $ 3,608 2022 ​ ​ 126,557 2023 ​ ​ 4,500 2024 ​ ​ 203,750 2025 ​ ​ 3,000 2026 ​ ​ 201,500 Total future minimum payments under the convertible senior notes ​ 542,915 Less: amounts representing interest ​ ​ (22,216) Less: unamortized debt discount ​ ​ (72,959) Less: unamortized debt issuance costs ​ ​ (5,733) Convertible senior notes balance ​ $ 442,007 (1) For the six months ending December 31, 2021. ​ As of June 30, 2021, $120.7 million in aggregate principal amount of the 2022 Convertible Notes was due within the next 12 months and is classified as current liabilities on the Company’s condensed consolidated balance sheets. Convertible Note Hedge and Note Hedge Warrant Transactions with Respect to 2022 Convertible Notes To minimize the impact of potential dilution to the Company's Class A common stockholders upon conversion of the 2022 Convertible Notes, the Company entered into the Convertible Note Hedges covering 20,249,665 shares of the Company’s Class A Common Stock in connection with the issuance of the 2022 Convertible Notes. The Convertible Note Hedges had an initial exercise price of $16.58 per share, subject to adjustment upon the occurrence of certain corporate events or transactions, and are exercisable if the 2022 Convertible Notes are converted. In connection with the adjustment to the conversion rate of the 2022 Convertible Notes related to the Separation in April 2019, the exercise price of the Convertible Note Hedges was adjusted to $14.51 per share and the number of shares underlying the Convertible Note Hedges was increased to 23,135,435 shares. If upon conversion of the 2022 Convertible Notes, the price of the Company’s Class A Common Stock is above the exercise price of the Convertible Note Hedges, the counterparties are obligated to deliver shares of the Company’s Class A Common Stock and/or cash with an aggregate value equal to the difference between the price of the Company’s Class A Common Stock at the conversion date and the exercise price, multiplied by the number of shares of the Company’s Class A Common Stock related to the Convertible Note Hedge being exercised. Concurrently with entering into the Convertible Note Hedges, the Company sold Note Hedge Warrants to the Convertible Note Hedge counterparties to acquire 20,249,665 shares of the Company’s Class A Common Stock, subject to customary anti-dilution adjustments. The strike price of the Note Hedge Warrants was initially $21.50 per share, subject to adjustment, and such warrants are exercisable over the 150 trading day period beginning on September 15, 2022. In connection with the Separation in April 2019, the exercise price was adjusted to $18.82 per share and the number of shares underlying the Note Hedge Warrants was increased to 23,135,435 shares. The Note Hedge Warrants could have a dilutive effect on the Class A Common Stock to the extent that the market price per share of the Company’s Class A Common Stock exceeds the applicable strike price of such warrants. The Convertible Note Hedges and the Note Hedge Warrants are separate transactions entered into by the Company and are not part of the terms of the 2022 Convertible Notes. Holders of the Convertible Note Hedges and the Note Hedge Warrants do not have any rights with respect to the 2022 Convertible Notes. The Company paid $91.9 million for the Convertible Note Hedges and received $70.8 million for the Note Hedge Warrants, resulting in a net cost to the Company of $21.1 million. In August 2019, concurrently with the repurchase of $215.0 million aggregate principal amount of the 2022 Convertible Notes, the Company terminated the respective portion of the Convertible Note Hedges and Note Hedge Warrants. The Company received $3.2 million of termination payments from the counterparties of the Convertible Note Hedges and Note Hedge Warrants. ​ The Convertible Note Hedges and Note Hedge Warrants are accounted for as derivative assets and liabilities, respectively, in accordance with ASC 815, and are remeasured to fair value at each reporting date (Note 5). As of June 30, 2021, the Convertible Note Hedges and Note Hedge Warrants were classified as current assets and non-current liabilities, respectively, on the Company’s condensed consolidated balance sheets. As of June 30, 2020, the Convertible Note Hedges and Note Hedge Warrants were classified as non-current assets and non-current liabilities, respectively, on the Company’s condensed consolidated balance sheets. Capped Calls with Respect to 2024 Convertible Notes and 2026 Convertible Notes ​ To minimize the impact of potential dilution to the Company’s Class A common stockholders upon conversion of the 2024 Convertible Notes and the 2026 Convertible Notes, the Company entered into separate Capped Calls in connection with the issuance of the 2024 Convertible Notes and the 2026 Convertible Notes. The Company paid the counterparties $25.2 million to enter into the Capped Calls. ​ The Capped Calls have an initial strike price of $13.39 per share, which corresponds to the initial conversion price of the 2024 Convertible Notes and the 2026 Convertible Notes and is subject to anti-dilution adjustments generally similar to those applicable to the 2024 Convertible Notes and the 2026 Convertible Notes. The Capped Calls have a cap price of $17.05 per share, subject to certain adjustments. The Capped Calls cover 29,867,480 shares of Class A Common Stock (subject to anti-dilution and certain other adjustments), which is the same number of shares of Class A Common Stock that initially underlie the 2024 Convertible Notes and the 2026 Convertible Notes. ​ The Capped Calls are expected generally to reduce the potential dilution to the Class A Common Stock upon conversion of the 2024 Convertible Notes and the 2026 Convertible Notes in the event that the market price per share of Class A Common Stock is greater than the strike price of the Capped Calls as adjusted pursuant to the anti-dilution adjustments. If, however, the market price per share of Class A Common Stock exceeds the cap price of the Capped Calls, there would nevertheless be dilution upon conversion of the 2024 Convertible Notes and the 2026 Convertible Notes to the extent that such market price exceeds the cap price of the Capped Calls. ​ The Capped Calls are separate transactions entered into by and between the Company and the Capped Calls counterparties and are not part of the terms of the 2024 Convertible Notes or the 2026 Convertible Notes. Holders of the 2024 Convertible Notes and the 2026 Convertible Notes do not have any rights with respect to the Capped Calls. The Company recorded a reduction to additional paid-in capital of $25.0 million during the year ended December 31, 2019 related to the premium payments for the Capped Calls. Additionally, the Company recorded an $0.2 million reduction to equity related to transaction costs incurred in connection with the Capped Calls during the year ended December 31, 2019. These instruments meet the conditions outlined in ASC 815 to be classified in stockholders’ equity and are not subsequently remeasured as long as the conditions for equity classification continue to be met.

Employee Stock Benefit Plans

Employee Stock Benefit Plans	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Employee Stock Benefit Plans	9. Employee Stock Benefit Plans ​ The Company has several share-based compensation plans under which stock options, restricted stock awards, restricted stock units and other share-based awards are available for grant to employees, officers, directors and consultants of the Company. ​ The following table summarizes share-based compensation expense (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2021 2020 2021 2020 Share-based compensation expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Research and development ​ $ 1,134 ​ $ 1,405 ​ $ 2,377 ​ $ 2,801 Selling, general and administrative ​ ​ 3,455 ​ 5,686 ​ 7,498 ​ ​ 10,654 Restructuring expenses ​ ​ — ​ ​ — ​ 110 ​ — Total share-based compensation expense ​ $ 4,589 ​ $ 7,091 ​ $ 9,985 ​ $ 13,455 ​ ​ Restructuring expenses include modifications to share-based awards held by employees impacted by certain

Stock Repurchase Plan

Stock Repurchase Plan	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Share Repurchase Plan	10. Share Repurchase Plan

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Income Taxes	11. Income Taxes For the three and six months ended June 30, 2021, the Company recorded an income tax benefit of $336.9 million and $336.5 million, respectively. The income tax benefit primarily pertains to the discrete income tax benefit of $337.8 million related to the release of the valuation allowance on the majority of the Company’s tax attributes and other deferred tax assets, partially offset by state income taxes in certain states which have temporarily disallowed the use of net operating losses to offset taxable income. There was no income tax provision for either the three or six months ended June 30, 2020. The income tax provision during interim periods is computed by applying an estimated annual effective income tax rate to year-to-date pre-tax income, plus adjustments for significant unusual or infrequently occurring items, in accordance with ASC 740-270, Income Taxes – Interim Reporting The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax bases of assets and liabilities. These differences are measured using the enacted statutory tax rates that are expected to be in effect for the years in which differences are expected to reverse. On a periodic basis, the Company reassesses any valuation allowances that it maintains on its deferred tax assets, weighing positive and negative evidence to assess the recoverability of the deferred tax assets. During the three months ended June 30, 2021, the Company reassessed the valuation allowance noting the shift of positive evidence outweighing negative evidence, including: continued strong prescription demand growth of LINZESS, nine consecutive quarters of profitability of a GI focused business since completing the tax-free spin-off of Cyclerion, and expectations regarding future profitability. After assessing both the positive evidence and negative evidence, the Company determined it was more likely than not that it will realize the majority of its deferred tax assets and during the three months ended June 30, 2021 released the majority of its valuation allowance, as a discrete item, for the deferred tax assets that are expected to be utilized in future years. The Company will maintain a valuation allowance on certain tax credits that are expected to expire prior to utilization.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Related Party Transactions	12. Related Party Transactions ​ The Company previously reflected balances with Allergan plc prior to its acquisition by AbbVie in May 2020 as related party receivables and payables, as appropriate. Following the acquisition of Allergan plc by AbbVie, the Company determined that AbbVie is not a related party to the Company. ​ In connection with the Separation, the Company executed certain contracts with Cyclerion, whose President and Chief Scientific Officer at the time of the Separation became a member of the Company’s Board of Directors in April 2019. As of December 31, 2020, the Company determined that Cyclerion was no longer considered a related party. The Company incurred $0.8 million and $1.8 million, respectively, of research and development expenses under a development agreement with Cyclerion during the three and six months ended June 30, 2020. Additionally, the Company incurred an insignificant amount of selling, general and administrative expenses for services provided by Cyclerion and recorded an insignificant amount of other income for services provided to Cyclerion during the three months ended March 31, 2020 under transition services agreements, which terminated on March 31, 2020. ​

Workforce Reduction and Restruc

Workforce Reduction and Restructuring	6 Months Ended
	Jun. 30, 2021
Disclosure Text Block
Workforce Reduction and Restructuring	13. Workforce Reduction and Restructuring ​ In September 2020, the Company announced that one of its two identical Phase III trials evaluating IW-3718 in refractory GERD did not meet certain criteria, including the study’s primary endpoint of achieving a statistically significant improvement in heartburn severity. Based on these findings, the Company discontinued development of IW-3718. In connection with this decision, the Company reduced its workforce by approximately 100 full-time employees. This workforce reduction affected both field-based and home-office employees, including the relevant general and administrative support functions, and was substantially completed during the fourth quarter of 2020. During the three and six months ended June 30, 2021, the Company reversed $0.3 million and recorded an insignificant amount, respectively, of restructuring expenses primarily comprised of employee severance, benefits and related costs. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ Accrued at ​ ​ ​ ​ ​ ​ ​ ​ ​ Accrued at ​ December 31, 2020 Charges ​ Amount Paid ​ Adjustments ​ June 30, 2021 Employee severance, benefits and related costs $ 10,902 ​ $ 1,025 ​ ​ (9,056) ​ ​ (594) ​ $ 2,277 Contract related costs ​ 5 ​ ​ 48 ​ ​ (53) ​ ​ — ​ ​ — Total $ 10,907 ​ $ 1,073 ​ $ (9,109) ​ $ (594) ​ $ 2,277 ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
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Basis of Presentation	Basis of Presentation ​ The accompanying condensed consolidated financial statements and the related disclosures are unaudited and have been prepared in accordance with accounting principles generally accepted in the U.S. Additionally, certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. Accordingly, these interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2020, which was filed with the Securities and Exchange Commission on February 17, 2021 (the “2020 Annual Report on Form 10-K”). ​ The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and, in the opinion of management, reflect all normal recurring adjustments considered necessary for a fair statement of the Company’s financial position as of June 30, 2021, and the results of its operations for the three and six months ended June 30, 2021 and 2020, its statements of stockholders’ equity for the three and six months ended June 30, 2021 and 2020, and its cash flows for the six months ended June 30, 2021 and 2020. The results of operations for the three and six months ended June 30, 2021 and 2020 are not necessarily indicative of the results that may be expected for the full year or any other subsequent interim period.
Principles of Consolidation	Principles of Consolidation ​ The accompanying condensed consolidated financial statements include the accounts of Ironwood and its wholly-owned subsidiaries as of June 30, 2021, Ironwood Pharmaceuticals Securities Corporation and Ironwood Pharmaceuticals GmbH. All intercompany transactions and balances are eliminated in consolidation.
Use of Estimates	Use of Estimates ​ The preparation of condensed consolidated financial statements in accordance with U.S. generally accepted accounting principles requires the Company’s management to make estimates and judgments that may affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the amounts of revenues and expenses during the reported periods. On an ongoing basis, the Company’s management evaluates its estimates, judgments and methodologies. Significant estimates and assumptions in the condensed consolidated financial statements include those related to revenue recognition; accounts receivable; useful lives of long-lived assets, impairment of long-lived assets, including goodwill; valuation procedures for right-of-use assets and operating lease liabilities; valuation procedures for the issuance and repurchase of convertible notes; balance sheet classification of convertible notes; fair value of derivatives; income taxes, including the valuation allowance for deferred tax assets; research and development expenses; contingencies and share-based compensation. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results may differ materially from these estimates under different assumptions or conditions. Changes in estimates are reflected in reported results in the period in which they become known.
Reclassifications	Reclassifications ​
New Accounting Pronouncements	New Accounting Pronouncements ​ From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (the “FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. ​ In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , ​ In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging— Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity In May 2021, the FASB issued ASU No. 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options Other recent accounting pronouncements issued, but not yet effective, are not expected to be applicable to the Company or have a material effect on the condensed consolidated financial statements upon future adoption. ​

Net Income Per Share (Tables)

Net Income Per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Schedule of computation of basic and diluted net loss per common share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2021 2020 ​ 2021 ​ 2020 Numerator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income ​ $ 391,303 ​ $ 25,204 ​ $ 431,229 ​ $ 28,549 Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average number of common shares outstanding used in computing net income per share — basic ​ ​ 161,948 ​ ​ 159,407 ​ 161,460 ​ 158,890 Effect of dilutive securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Stock options ​ ​ 417 ​ ​ 244 ​ ​ 348 ​ ​ 465 Time-based restricted stock units ​ ​ 928 ​ ​ 153 ​ ​ 1,121 ​ ​ 552 Performance-based restricted stock units ​ ​ 70 ​ ​ — ​ ​ 71 ​ ​ — Restricted stock ​ ​ 132 ​ ​ 116 ​ ​ 134 ​ ​ 125 Dilutive potential common shares ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average number of common shares outstanding used in computing net income per share — diluted ​ ​ 163,495 ​ ​ 159,920 ​ ​ 163,134 ​ 160,032 Net income per share — basic ​ $ 2.42 ​ $ 0.16 ​ $ 2.67 ​ $ 0.18 Net income per share — diluted ​ $ 2.39 ​ $ 0.16 ​ $ 2.64 ​ $ 0.18 ​
Schedule of potentially dilutive securities that have been excluded from computation of diluted weighted average shares outstanding	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ ​ 2021 2020 ​ 2021 2020 Stock options ​ 9,430 ​ 12,360 ​ 10,007 14,828 ​ Restricted stock awards — ​ — ​ 36 — ​ Shares subject to repurchase ​ — ​ — ​ — ​ 174 ​ Time-based restricted stock units ​ 84 ​ 3,134 ​ 53 ​ 5,012 ​ Performance-based restricted stock units ​ 619 ​ — ​ 330 ​ 586 ​ Note Hedge Warrants ​ 8,318 ​ 8,318 ​ 8,318 ​ 8,318 ​ 2022 Convertible Notes ​ 8,318 ​ 8,318 ​ 8,318 ​ 8,318 ​ 2024 Convertible Notes ​ 14,934 ​ 14,934 ​ 14,934 ​ 14,934 ​ 2026 Convertible Notes ​ 14,934 ​ 14,934 ​ 14,934 ​ 14,934 ​ Total 56,637 61,998 ​ 56,930 67,104 ​ ​

Collaboration, License, Promo_2

Collaboration, License, Promotion and Other Commercial Agreements (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Schedule of revenue attributable to transactions from collaboration and license arrangements	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, Collaborative Arrangements Revenue ​ 2021 2020 ​ 2021 2020 Linaclotide Collaboration and License Agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AbbVie (North America) ​ $ 101,038 ​ $ 86,926 ​ $ 187,537 ​ $ 158,618 AbbVie (Europe and other) ​ ​ 574 ​ ​ 440 ​ ​ 1,174 ​ ​ 1,083 AstraZeneca (China, including Hong Kong and Macau) ​ ​ 200 ​ 187 ​ ​ 410 ​ 519 Astellas (Japan) ​ ​ 570 ​ 504 ​ ​ 1,066 ​ 983 Co-Promotion and Other Agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Alnylam (GIVLAARI) ​ ​ 596 ​ ​ 1,061 ​ ​ 1,052 ​ ​ 2,006 Other ​ ​ 408 ​ ​ 305 ​ ​ 812 ​ ​ 659 Total collaborative arrangements revenue ​ $ 103,386 ​ $ 89,423 ​ $ 192,051 ​ $ 163,868 Sale of API ​ ​ ​ ​ ​ Linaclotide Agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ AstraZeneca (China, including Hong Kong and Macau) ​ ​ 576 ​ ​ 9 ​ ​ 597 ​ ​ 5,507 Other ​ ​ 69 ​ ​ — ​ ​ 228 ​ ​ — Total sale of API ​ $ 645 ​ $ 9 ​ $ 825 ​ $ 5,507 ​
AbbVie
Table Text Blocks
Schedule of revenue attributable to transactions from collaboration and license arrangements	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2021 2020 2021 2020 Collaborative arrangements revenue related to sales of LINZESS in the U.S. ​ $ 100,307 ​ $ 86,503 ​ $ 186,256 ​ $ 157,645 Royalty revenue ​ 731 ​ 423 ​ 1,281 ​ ​ 973 Total collaborative arrangements revenue ​ $ 101,038 ​ $ 86,926 ​ $ 187,537 ​ $ 158,618

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Schedule of assets and liabilities measured at fair value on a recurring basis	The following tables present the assets and liabilities the Company has measured at fair value on a recurring basis (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using ​ ​ ​ Quoted Prices in Significant Other Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ June 30, 2021 ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 476,684 ​ ​ $ 476,684 ​ ​ — ​ ​ — Restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ ​ 2,220 ​ ​ ​ 2,220 ​ ​ — ​ ​ — Convertible note hedges ​ ​ 11,262 ​ ​ ​ — ​ ​ — ​ ​ 11,262 Total assets measured at fair value ​ $ 490,166 ​ ​ $ 478,904 ​ $ — ​ $ 11,262 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Note hedge warrants ​ $ 11,061 ​ ​ $ — ​ ​ — ​ ​ 11,061 Total liabilities measured at fair value ​ $ 11,061 ​ ​ $ — ​ $ — ​ $ 11,061 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at Reporting Date Using ​ ​ ​ Quoted Prices in Significant Other Significant ​ ​ ​ ​ ​ ​ Active Markets for ​ Observable ​ Unobservable ​ ​ ​ ​ ​ Identical Assets ​ Inputs ​ Inputs ​ ​ December 31, 2020 ​ ​ (Level 1) ​ (Level 2) ​ (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ $ 349,014 ​ ​ $ 349,014 ​ $ — ​ $ — Restricted cash: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Money market funds ​ 2,221 ​ ​ 2,221 ​ — ​ — Convertible note hedges ​ ​ 13,065 ​ ​ ​ — ​ ​ — ​ ​ 13,065 Total assets measured at fair value ​ $ 364,300 ​ ​ $ 351,235 ​ $ — ​ $ 13,065 Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Note hedge warrants ​ $ 12,088 ​ ​ $ — ​ $ — ​ $ 12,088 Total liabilities measured at fair value ​ $ 12,088 ​ ​ $ — ​ $ — ​ $ 12,088 ​
Schedule of assumptions used in fair market valuations	The following inputs were used in the fair market valuation of the Convertible Note Hedges and Note Hedge Warrants as of June 30, 2021 and December 31, 2020: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six Months Ended ​ Year Ended ​ ​ ​ June 30, 2021 ​ December 31, 2020 ​ ​ ​ Convertible Note Hedge ​ Convertible Note Hedge ​ ​ Note Hedges ​ Warrants Note Hedges ​ Warrants Risk-free interest rate (1) ​ ​ 0.1 % ​ 0.2 % ​ 0.1 % ​ 0.1 % Expected term ​ 1.0 ​ 1.5 ​ ​ 1.5 ​ 2.0 ​ Stock price (2) ​ $ 12.87 ​ $ 12.87 ​ $ 11.39 ​ $ 11.39 ​ Strike price (3) ​ $ 14.51 ​ $ 18.82 ​ $ 14.51 ​ $ 18.82 ​ Common stock volatility (4) ​ ​ 39.0 % ​ 46.1 % ​ 46.7 % ​ 50.3 % Dividend yield (5) ​ — % — % — % — % (1) Based on U.S. Treasury yield curve, with terms commensurate with the expected terms of the Convertible Note Hedges and the Note Hedge Warrants. (2) The closing price of the Company’s Class A Common Stock on the last trading days of the quarters ended June 30, 2021 and December 31, 2020, respectively. (3) As per the respective agreements for the Convertible Note Hedges and Note Hedge Warrants. (4) Expected volatility based on historical volatility of the Company’s Class A Common Stock. (5) The Company has not paid and does not anticipate paying cash dividends on its shares of common stock in the foreseeable future; therefore, the expected dividend yield is assumed to be zero.
Schedule of the change in Level 3 convertible note derivatives	The following table reflects the change in the Company’s Level 3 Convertible Note Hedges and Note Hedge Warrants from December 31, 2020 through June 30, 2021 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Convertible ​ Note Hedge ​ Note Hedges Warrants Balance at December 31, 2020 ​ $ 13,065 ​ $ (12,088) Change in fair value, recorded as a component of (loss) gain on derivatives ​ ​ (1,803) ​ ​ 1,027 Balance at June 30, 2021 ​ $ 11,262 ​ $ (11,061) ​

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 December 31, 2020 Accrued incentive compensation ​ $ 6,879 ​ $ 8,719 Accrued vacation ​ ​ 2,400 ​ ​ 2,625 Professional fees ​ 1,283 ​ 530 Salaries ​ ​ 972 ​ ​ 627 Other employee benefits ​ ​ 438 ​ ​ 1,442 Restructuring liabilities ​ ​ 2,124 ​ ​ 10,510 Other ​ 2,157 ​ 2,033 Total accrued expenses and other current liabilities ​ $ 16,253 ​ $ 26,486

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Schedule of components of lease cost and supplemental cash flow information	Lease cost is recognized on a straight-line basis over the lease term. The components of lease cost for the three and six months ended June 30, 2021 and 2020 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ ​ June 30, ​ June 30, ​ ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 ​ Operating lease cost ​ $ 630 ​ $ 633 ​ $ 1,261 ​ $ 1,266 ​ Short-term lease cost ​ ​ 214 ​ ​ 360 ​ ​ 428 ​ ​ 732 ​ Total lease cost ​ $ 844 ​ $ 993 ​ $ 1,689 ​ $ 1,998 ​ ​ Supplemental information related to leases for the periods reported is as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Six Months Ended June 30, ​ ​ ​ 2021 ​ 2020 Cash paid for amounts included in the measurement of lease liabilities (in thousands) ​ ​ $ 778 ​ ​ $ 86 ​ Weighted-average remaining lease term of operating leases (in years) ​ ​ ​ 8.8 ​ ​ ​ 9.7 ​ Weighted-average discount rate of operating leases ​ ​ ​ 5.8 % ​ ​ 5.8 % ​
Schedule of future minimum lease payments under non-cancelable operating leases	Future minimum lease payments under non-cancelable operating leases as of June 30, 2021 are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ Operating ​ Lease ​ ​ Payments 2021 (1) ​ $ 1,578 2022 ​ ​ 3,129 2023 ​ ​ 3,065 2024 ​ ​ 3,126 2025 ​ 3,189 2026 and thereafter ​ 14,855 Total future minimum lease payments ​ ​ 28,942 Less: present value adjustment ​ ​ (6,387) Operating lease liabilities at June 30, 2021 ​ ​ 22,555 Less: current portion of operating lease liabilities ​ ​ (3,161) Operating lease liabilities, net of current portion ​ $ 19,394 (1) For the six months ending December 31, 2021.

Notes Payable (Tables)

Notes Payable (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Schedule of outstanding Convertible Note	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ June 30, 2021 ​ December 31, 2020 ​ ​ ​ ​ ​ ​ ​ Liability component: ​ ​ ​ ​ ​ ​ Principal: ​ ​ ​ ​ ​ ​ 2022 Convertible Notes ​ $ 120,699 ​ $ 120,699 2024 Convertible Notes ​ ​ 200,000 ​ ​ 200,000 2026 Convertible Notes ​ ​ 200,000 ​ ​ 200,000 Less: unamortized debt discount ​ ​ (72,959) ​ ​ (83,900) Less: unamortized debt issuance costs ​ ​ (5,733) ​ ​ (6,543) Net carrying amount ​ $ 442,007 ​ $ 430,256 Equity component: ​ ​ ​ ​ ​ ​ 2022 Convertible Notes ​ ​ 19,807 ​ ​ 19,807 2024 Convertible Notes ​ ​ 41,152 ​ ​ 41,152 2026 Convertible Notes ​ ​ 51,350 ​ ​ 51,350 Total equity component ​ $ 112,309 ​ $ 112,309
Schedule of interest expense related to Convertible Notes	​ The following table sets forth total interest expense recognized related to convertible senior notes during the three and six months ended June 30, 2021 and 2020 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2021 2020 2021 2020 Contractual interest expense ​ $ 1,804 ​ $ 1,802 ​ $ 3,607 ​ $ 3,609 Amortization of debt issuance costs ​ ​ 412 ​ ​ 360 ​ ​ 811 ​ ​ 705 Amortization of debt discount ​ ​ 5,516 ​ ​ 5,156 ​ ​ 10,940 ​ ​ 10,224 Total interest expense ​ $ 7,732 ​ $ 7,318 ​ $ 15,358 ​ $ 14,538
Schedule of future minimum payments details of debt	Future minimum payments under the convertible senior notes as of June 30, 2021, are as follows (in thousands): ​ ​ ​ ​ 2021 (1) ​ $ 3,608 2022 ​ ​ 126,557 2023 ​ ​ 4,500 2024 ​ ​ 203,750 2025 ​ ​ 3,000 2026 ​ ​ 201,500 Total future minimum payments under the convertible senior notes ​ 542,915 Less: amounts representing interest ​ ​ (22,216) Less: unamortized debt discount ​ ​ (72,959) Less: unamortized debt issuance costs ​ ​ (5,733) Convertible senior notes balance ​ $ 442,007 (1) For the six months ending December 31, 2021.

Employee Stock Benefit Plans (T

Employee Stock Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Share-based compensation expense reflected in the condensed consolidated statements of operations	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Six Months Ended ​ ​ June 30, ​ June 30, ​ 2021 2020 2021 2020 Share-based compensation expense: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Research and development ​ $ 1,134 ​ $ 1,405 ​ $ 2,377 ​ $ 2,801 Selling, general and administrative ​ ​ 3,455 ​ 5,686 ​ 7,498 ​ ​ 10,654 Restructuring expenses ​ ​ — ​ ​ — ​ 110 ​ — Total share-based compensation expense ​ $ 4,589 ​ $ 7,091 ​ $ 9,985 ​ $ 13,455 ​

Workforce Reduction and Restr_2

Workforce Reduction and Restructuring (Tables)	6 Months Ended
	Jun. 30, 2021
Table Text Blocks
Schedule of charges made to the reduction in field-based workforce	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Amounts ​ Accrued at ​ ​ ​ ​ ​ ​ ​ ​ ​ Accrued at ​ December 31, 2020 Charges ​ Amount Paid ​ Adjustments ​ June 30, 2021 Employee severance, benefits and related costs $ 10,902 ​ $ 1,025 ​ ​ (9,056) ​ ​ (594) ​ $ 2,277 Contract related costs ​ 5 ​ ​ 48 ​ ​ (53) ​ ​ — ​ ​ — Total $ 10,907 ​ $ 1,073 ​ $ (9,109) ​ $ (594) ​ $ 2,277

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details)	Jun. 30, 2021
Accounting Standards Update 2019-12
New Accounting Pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	true
Change in Accounting Principle, Accounting Standards Update, Early Adoption	false
Accounting Standards Update 2020-06
New Accounting Pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	false
Change in Accounting Principle, Accounting Standards Update, Early Adoption	false
Accounting Standards Update 2021-04
New Accounting Pronouncements
Change in Accounting Principle, Accounting Standards Update, Adopted	false
Change in Accounting Principle, Accounting Standards Update, Early Adoption	false

Net Income Per Share - Computat

Net Income Per Share - Computation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Numerator:
Net income	$ 391,303	$ 39,926	$ 25,204	$ 3,345	$ 431,229	$ 28,549
Net income (loss) available to common stockholders, basic	391,303		25,204		431,229	28,549
Net income (loss) available to common stockholders, diluted	$ 391,303		$ 25,204		$ 431,229	$ 28,549
Denominator:
Weighted average number of common shares outstanding used in computing net income per share - basic (in shares)	161,948		159,407		161,460	158,890
Effect of dilutive securities:
Weighted average number of common shares outstanding used in computing net income per share - diluted (in shares)	163,495		159,920		163,134	160,032
Net income per share - basic (in dollars per share)	$ 2.42		$ 0.16		$ 2.67	$ 0.18
Net income per share - diluted (in dollars per share)	$ 2.39		$ 0.16		$ 2.64	$ 0.18
Employee stock options
Effect of dilutive securities:
Effect of dilutive securities	417		244		348	465
Time-based Restricted Stock Units
Effect of dilutive securities:
Effect of dilutive securities	928		153		1,121	552
Performance-based Restricted Stock Units
Effect of dilutive securities:
Effect of dilutive securities	70				71
Restricted Stock
Effect of dilutive securities:
Effect of dilutive securities	132		116		134	125

Net Income Per Share - Potentia

Net Income Per Share - Potentially Dilutive Securities (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	56,637	61,998	56,930	67,104
Employee stock options
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	9,430	12,360	10,007	14,828
Restricted Stock
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)			36
Shares subject to repurchase
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)				174
Time-based Restricted Stock Units
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	84	3,134	53	5,012
Performance-based Restricted Stock Units
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	619		330	586
Note Hedge Warrants
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	8,318	8,318	8,318	8,318
2.25% Convertible Senior Notes due 2022
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	8,318	8,318	8,318	8,318
0.75% Convertible Senior Notes due 2024
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	14,934	14,934	14,934	14,934
1.50% Convertible Senior Notes due 2026
Potentially dilutive securities
Total potentially dilutive securities excluded from the computation of diluted weighted average shares outstanding (in shares)	14,934	14,934	14,934	14,934

Collaboration, License, Promo_3

Collaboration, License, Promotion and Other Commercial Agreements - Summary (Details) - USD ($) $ in Thousands	Aug. 01, 2019	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenue		$ 104,031	$ 89,432	$ 192,876	$ 169,375
Collaborative arrangements revenue
Revenues:
Revenue		103,386	89,423	192,051	163,868
Collaborative arrangement, other agreements
Revenues:
Revenue		408	305	812	659
Sale of active pharmaceutical ingredient
Revenues:
Revenue		645	9	825	5,507
AbbVie | Sale of active pharmaceutical ingredient
Revenues:
Revenue		69		228
AbbVie | North America | Collaborative arrangements revenue
Revenues:
Revenue		101,038	86,926	187,537	158,618
AbbVie | North America | Collaborative arrangement, collaboration and license agreements
Revenues:
Revenue		101,038	86,926	187,537	158,618
AbbVie | Europe and Other | Collaborative arrangement, collaboration and license agreements
Revenues:
Revenue		574	440	1,174	1,083
AstraZeneca | Collaborative arrangement, collaboration and license agreements
Revenues:
Revenue		200	187	410	519
AstraZeneca | Sale of active pharmaceutical ingredient
Revenues:
Revenue		576	9	597	5,507
Astellas Pharma Inc. | Collaborative arrangement, collaboration and license agreements
Revenues:
Revenue	$ 20,400
Alnylam | Collaborative arrangement, co-promotion agreements
Revenues:
Revenue		$ 596	$ 1,061	$ 1,052	$ 2,006

Collaboration, License, Promo_4

Collaboration, License, Promotion and Other Commercial Agreements - Accounts Receivable (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts receivable, net
Accounts receivable, net	$ 126	$ 145.8
Accounts receivable, net of accounts payable	99.9	110.9
AbbVie
Accounts receivable, net
Accounts payable	$ 3.7	$ 4.3

Collaboration, License, Promo_5

Collaboration, License, Promotion and Other Commercial Agreements - North America - General Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)paymentitem	Jun. 30, 2020USD ($)
Collaboration, License, Promotion and Other Commercial Agreements
Research and development expense	$ 12,163	$ 22,076	$ 27,647	$ 50,103
AbbVie
Collaboration, License, Promotion and Other Commercial Agreements
Cumulative license fees and development milestone payments received	205,000		$ 205,000
Number of milestone payments received | payment			6
Equity investment in the entity's capital stock			$ 25,000
Sales-related milestone if certain conditions are met	80,000		$ 80,000
Remaining commercial-period performance obligations | item			3
Cost sharing amount, reduction to research and development	2,800	500	$ 5,700	1,200
Collaborative arrangement, percentage of obligation of development costs incurred			50.00%
Percentage of net profit from commercialization (as a percent)			50.00%
Percentage of net loss from commercialization (as a percent)			50.00%
North America
Collaboration, License, Promotion and Other Commercial Agreements
Research and development expense	$ 1,800	$ 6,200	$ 3,600	$ 12,900

Collaboration, License, Promo_6

Collaboration, License, Promotion and Other Commercial Agreements - North America - Collaborative Arrangements Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenue	$ 104,031	$ 89,432	$ 192,876	$ 169,375
Collaborative arrangements revenue
Revenues:
Revenue	103,386	89,423	192,051	163,868
AbbVie | North America | Collaborative arrangements revenue
Revenues:
Revenue	101,038	86,926	187,537	158,618
AbbVie | North America | Collaborative arrangements, LINZESS
Revenues:
Revenue	100,307	86,503	186,256	157,645
AbbVie | North America | Royalty
Revenues:
Revenue	$ 731	$ 423	$ 1,281	$ 973

Collaboration, License, Promo_7

Collaboration, License, Promotion and Other Commercial Agreements - North America - Commercial Efforts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	$ 104,031	$ 89,432	$ 192,876	$ 169,375
Selling, general and administrative costs incurred by the Company	27,052	34,643	54,704	71,093
AbbVie | U.S.
Collaboration, License, Promotion and Other Commercial Agreements
Patent litigation costs				400
Collaborative arrangements revenue
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	103,386	89,423	192,051	163,868
Collaborative arrangements, LINZESS | AbbVie | U.S.
Collaboration, License, Promotion and Other Commercial Agreements
Selling, general and administrative costs incurred by the Company	$ 7,500	$ 4,100	$ 14,500	$ 13,000

Collaboration, License, Promo_8

Collaboration, License, Promotion and Other Commercial Agreements - North America - Royalty Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues:
Revenue	$ 104,031	$ 89,432	$ 192,876	$ 169,375
Collaborative arrangements revenue
Revenues:
Revenue	103,386	89,423	192,051	163,868
Collaborative arrangements revenue | North America | AbbVie
Revenues:
Revenue	101,038	86,926	187,537	158,618
Royalty | North America | AbbVie
Revenues:
Revenue	731	423	1,281	973
Royalty | Canada and Mexico | AbbVie
Revenues:
Revenue	$ 700	$ 400	$ 1,300	$ 1,000

Collaboration, License, Promo_9

Collaboration, License, Promotion and Other Commercial Agreements - European and Other Territories (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Oct. 31, 2015	Sep. 30, 2012
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	$ 104,031	$ 89,432	$ 192,876	$ 169,375
Collaborative arrangements revenue
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	103,386	89,423	$ 192,051	163,868
License | AbbVie
Collaboration, License, Promotion and Other Commercial Agreements
Royalty percentage, five years following the first commercial sale			upper-single digits
Annual royalty			5 years
Royalty percentage, thereafter			low-double digits
Royalty percentage, expanded territory			lower-single digits
License | AbbVie | Europe
Collaboration, License, Promotion and Other Commercial Agreements
Remaining milestone payment due upon the amendment to the license agreement					$ 42,500
Revenue remaining performance obligation						$ 0
Royalty | AbbVie | Europe
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	$ 600	$ 400	$ 1,200	$ 1,100

Collaboration, License, Prom_10

Collaboration, License, Promotion and Other Commercial Agreements - Japan (Details) $ in Thousands	Aug. 01, 2019USD ($)	Nov. 30, 2009USD ($)payment	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)
Collaboration, License, Promotion and Other Commercial Agreements
Revenue			$ 104,031	$ 89,432	$ 192,876	$ 169,375
Astellas Pharma Inc., 2009 License Agreement | Japan
Collaboration, License, Promotion and Other Commercial Agreements
Up-front fee received		$ 30,000
Number of milestone payments | payment		3
Milestone payments received		$ 45,000
Collaborative arrangements revenue
Collaboration, License, Promotion and Other Commercial Agreements
Revenue			103,386	89,423	192,051	163,868
Collaborative arrangements revenue | Astellas Pharma Inc., 2009 License Agreement, Amended 2019
Collaboration, License, Promotion and Other Commercial Agreements
Revenue				500		1,000
Collaborative arrangement, collaboration and license agreements | Astellas Pharma Inc.
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	$ 20,400
Collaborative arrangement, collaboration and license agreements | Astellas Pharma Inc. | Japan
Collaboration, License, Promotion and Other Commercial Agreements
Revenue			570	504	1,066	983
Non-refundable upfront payment	$ 10,000
Sale of active pharmaceutical ingredient
Collaboration, License, Promotion and Other Commercial Agreements
Revenue			645	9	825	5,507
Royalty | Astellas Pharma Inc., 2009 License Agreement, Amended 2019
Collaboration, License, Promotion and Other Commercial Agreements
Revenue			$ 600	$ 500	$ 1,100	$ 900

Collaboration, License, Prom_11

Collaboration, License, Promotion and Other Commercial Agreements - China, Hong Kong and Macau (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2021USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)installment
Collaboration, License, Promotion and Other Commercial Agreements
Revenue		$ 104,031	$ 89,432	$ 192,876	$ 169,375
Collaborative arrangements revenue
Collaboration, License, Promotion and Other Commercial Agreements
Revenue		103,386	89,423	192,051	163,868
Sale of active pharmaceutical ingredient
Collaboration, License, Promotion and Other Commercial Agreements
Revenue		645	9	825	5,507
AstraZeneca
Collaboration, License, Promotion and Other Commercial Agreements
Interest income			200		400
AstraZeneca | Collaborative arrangement, collaboration and license agreements
Collaboration, License, Promotion and Other Commercial Agreements
Revenue		200	187	410	519
AstraZeneca | Sale of active pharmaceutical ingredient
Collaboration, License, Promotion and Other Commercial Agreements
Revenue		$ 576	9	597	5,507
AstraZeneca | China, Hong Kong, and Macau | Collaborative arrangements revenue
Collaboration, License, Promotion and Other Commercial Agreements
Collaborative arrangement, significant financing component, transaction price	$ 2,600
Collaborative arrangement, expected interest income	2,600
AstraZeneca | China, Hong Kong, and Macau | Collaborative arrangement, collaboration agreements
Collaboration, License, Promotion and Other Commercial Agreements
Milestone payment to be received by company upon milestone achievement						$ 90,000
Amount of non-contingent arrangement consideration						$ 35,000
Non-contingent consideration installments | installment						3
Non-contingent arrangement consideration installment received	10,000
Percentage of tiered royalties						20.00%
AstraZeneca | China, Hong Kong, and Macau | Collaborative arrangement, transition services agreement
Collaboration, License, Promotion and Other Commercial Agreements
Regulatory and administrative services initial term						2 years
AstraZeneca License Agreement
Collaboration, License, Promotion and Other Commercial Agreements
Interest income				300
AstraZeneca License Agreement | Collaborative arrangement, collaboration agreements
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	$ 32,400
AstraZeneca License Agreement | Collaborative arrangement, transition services agreement
Collaboration, License, Promotion and Other Commercial Agreements
Revenue			$ 200	200	400
AstraZeneca License Agreement | Royalty
Collaboration, License, Promotion and Other Commercial Agreements
Revenue				$ 200	$ 200

Collaboration, License, Prom_12

Collaboration, License, Promotion and Other Commercial Agreements - Promotion Agreements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	$ 104,031	$ 89,432	$ 192,876	$ 169,375
Collaborative arrangements revenue
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	103,386	89,423	192,051	163,868
Alnylam | Collaborative arrangement, co-promotion agreements
Collaboration, License, Promotion and Other Commercial Agreements
Total annual service fees due					$ 5,500
Revenue	596	1,061	1,052	2,006
Alnylam | Service fees
Collaboration, License, Promotion and Other Commercial Agreements
Revenue		900		1,800
Alnylam | Royalty
Collaboration, License, Promotion and Other Commercial Agreements
Revenue	$ 600	$ 200	$ 1,100	$ 200

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - General Information (Details)	Jun. 30, 2020
Fair Value of Financial Instruments
Threshold percentage of collateralized value (as a percent)	102.00%

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Measured on Recurring Basis (Details) - Recurring basis - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets:
Convertible note hedges	$ 11,262	$ 13,065
Total assets measured at fair value	490,166	364,300
Liabilities:
Note hedge warrants	11,061	12,088
Total liabilities measured at fair value	11,061	12,088
Money market funds
Assets:
Cash and cash equivalents	476,684	349,014
Restricted cash	2,220	2,221
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total assets measured at fair value	478,904	351,235
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Assets:
Cash and cash equivalents	476,684	349,014
Restricted cash	2,220	2,221
Significant Unobservable Inputs (Level 3)
Assets:
Convertible note hedges	11,262	13,065
Total assets measured at fair value	11,262	13,065
Liabilities:
Note hedge warrants	11,061	12,088
Total liabilities measured at fair value	$ 11,061	$ 12,088

Fair Value of Financial Instr_5

Fair Value of Financial Instruments - Transfers Between Fair Value Measurement Levels (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Fair value transfers
Fair value transfer between measurement levels	$ 0	$ 0	$ 0	$ 0

Fair Value of Financial Instr_6

Fair Value of Financial Instruments - Assumptions - Convertible Note Hedges (Details)	Jun. 30, 2021$ / sharesY	Dec. 31, 2020$ / sharesY
Fair Value of Financial Instruments
Derivative asset, valuation technique	us-gaap:ValuationTechniqueOptionPricingModelMember	us-gaap:ValuationTechniqueOptionPricingModelMember
Measurement Input, Risk Free Interest Rate
Fair Value of Financial Instruments
Derivative asset, measurement input	0.001	0.001
Measurement Input, Expected Term
Fair Value of Financial Instruments
Derivative asset, measurement input | Y	1	1.5
Measurement Input, Share Price
Fair Value of Financial Instruments
Derivative asset, measurement input	12.87	11.39
Measurement Input, Exercise Price
Fair Value of Financial Instruments
Derivative asset, measurement input	14.51	14.51
Measurement Input, Price Volatility
Fair Value of Financial Instruments
Derivative asset, measurement input	0.390	0.467
Measurement Input, Expected Dividend Rate
Fair Value of Financial Instruments
Derivative asset, measurement input	0	0

Fair Value of Financial Instr_7

Fair Value of Financial Instruments - Assumptions - Note Hedge Warrants (Details)	Jun. 30, 2021Y$ / shares	Dec. 31, 2020Y$ / shares
Fair Value of Financial Instruments
Derivative liability, valuation technique	us-gaap:ValuationTechniqueOptionPricingModelMember	us-gaap:ValuationTechniqueOptionPricingModelMember
Measurement Input, Risk Free Interest Rate
Fair Value of Financial Instruments
Derivative liability, measurement input	0.002	0.001
Measurement Input, Expected Term
Fair Value of Financial Instruments
Derivative liability, measurement input | Y	1.5	2
Measurement Input, Share Price
Fair Value of Financial Instruments
Derivative liability, measurement input	12.87	11.39
Measurement Input, Exercise Price
Fair Value of Financial Instruments
Derivative liability, measurement input	18.82	18.82
Measurement Input, Price Volatility
Fair Value of Financial Instruments
Derivative liability, measurement input	0.461	0.503
Measurement Input, Expected Dividend Rate
Fair Value of Financial Instruments
Derivative liability, measurement input	0	0

Fair Value of Financial Instr_8

Fair Value of Financial Instruments - Change in Level 3 - Convertible Note Hedges (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Change in Level 3 Assets
Balance at beginning of period	$ 13,065
Change in fair value, recorded as a component of (loss) gain on derivatives	(1,803)
Balance at end of period	$ 11,262

Fair Value of Financial Instr_9

Fair Value of Financial Instruments - Change in Level 3 - Note Hedge Warrants (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Change in Level 3 Liabilities
Balance at beginning of period	$ (12,088)
Change in fair value, recorded as a component of gain (loss) on derivatives	(1,027)
Balance at end of period	$ (11,061)

Fair Value of Financial Inst_10

Fair Value of Financial Instruments - Notes Payable (Details) - Convertible Senior Notes - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Aug. 31, 2019	Jun. 30, 2015
2.25% Convertible Senior Notes due 2022
Fair value disclosures
Aggregate principal amount of notes issued	$ 120,699	$ 120,699		$ 335,700
Debt redeemed/repurchased			$ 215,000
2.25% Convertible Senior Notes due 2022 | Significant Other Observable Inputs (Level 2)
Fair value disclosures
Estimated fair value	131,100	130,200
0.75% Convertible Senior Notes due 2024
Fair value disclosures
Aggregate principal amount of notes issued	200,000	200,000	200,000
0.75% Convertible Senior Notes due 2024 | Significant Other Observable Inputs (Level 2)
Fair value disclosures
Estimated fair value	234,700	222,300
1.50% Convertible Senior Notes due 2026
Fair value disclosures
Aggregate principal amount of notes issued	200,000	200,000	$ 200,000
1.50% Convertible Senior Notes due 2026 | Significant Other Observable Inputs (Level 2)
Fair value disclosures
Estimated fair value	$ 239,200	$ 224,100

Fair Value of Financial Inst_11

Fair Value of Financial Instruments - Capped Calls with Respect to 2024 Convertible Notes and 2026 Convertible Notes (Details) - Capped Calls with Respect to 2024 Convertible Notes and 2026 Convertible Notes	1 Months Ended
	Aug. 31, 2019$ / shares$ / itemshares
Capped Calls
Number of shares covered by capped calls (in shares) | shares	29,867,480
Strike price (in dollars per share) | $ / shares	$ 13.39
Cap price | $ / item	17.05

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Tabular Disclosure (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued Expenses
Accrued incentive compensation	$ 6,879	$ 8,719
Accrued vacation	2,400	2,625
Professional fees	1,283	530
Salaries	972	627
Other employee benefits	438	1,442
Restructuring liabilities	2,124	10,510
Other	2,157	2,033
Total accrued expenses and other current liabilities	$ 16,253	$ 26,486

Accrued Expenses and Other Cu_4

Accrued Expenses and Other Current Liabilities - Additional Information (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued Expenses
Other accrued expenses	$ 2,157	$ 2,033
Other accrued liabilities, uninvoiced vendor liabilities	1,500	1,600
Accrued interest	$ 300	$ 300

Leases - Collateral (Details)

Leases - Collateral (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Restricted Cash [Abstract]
Restricted cash	$ 2,220		$ 2,221
Money market funds
Restricted Cash [Abstract]
Restricted cash	$ 2,200	$ 2,200

Leases - Lease Cost (Details)

Leases - Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lease cost
Operating lease cost during period, net	$ 630	$ 633	$ 1,261	$ 1,266
Short-term lease cost	214	360	428	732
Total lease cost	$ 844	$ 993	$ 1,689	$ 1,998

Leases - Supplemental Cash Flow

Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating leases
Cash paid for amounts included in the measurement of lease liabilities	$ 778	$ 86
Weighted-average remaining lease term of operating leases (in years)	8 years 9 months 18 days	9 years 8 months 12 days
Weighted-average discount rate of operating leases (as a percent)	5.80%	5.80%

Leases - Future Minimum Lease P

Leases - Future Minimum Lease Payments (Details) $ in Thousands	Jun. 30, 2021USD ($)
Future minimum lease payments
2021	$ 1,578
2022	3,129
2023	3,065
2024	3,126
2025	3,189
2026 and thereafter	14,855
Total future minimum lease payments	$ 28,942

Leases - Operating Lease Obliga

Leases - Operating Lease Obligations (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Operating lease obligations
Total future minimum lease payments	$ 28,942
Less: present value adjustment	(6,387)
Operating lease liabilities	22,555
Less: current portion of operating lease liabilities	(3,161)	$ (3,128)
Operating lease liabilities, net of current portion	$ 19,394	$ 20,318

Leases - Summer Street Lease (D

Leases - Summer Street Lease (Details) ft² in Thousands, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2019ft²	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Operating leases
Weighted-average discount rate of operating leases (as a percent)		5.80%	5.80%	5.80%	5.80%
Operating lease right-of-use assets		$ 15,975		$ 15,975		$ 16,576
Operating lease liability		22,555		22,555
Operating lease cost		$ 630	$ 633	$ 1,261	$ 1,266
Summer Street Lease
Operating leases
Rentable area leased (in square feet) | ft²	39
Annual rent escalation (as a percent)	2.00%
Option to extend the term of the lease	true
Operating lease, renewal term	5 years
Weighted-average discount rate of operating leases (as a percent)		5.80%		5.80%
Operating lease right-of-use assets		$ 16,000		$ 16,000		16,600
Operating lease liability		22,300		22,300		$ 23,200
Operating lease cost		$ 600	$ 700	$ 1,300	$ 1,300

Notes Payable - Convertible Sen

Notes Payable - Convertible Senior Notes - 2.25% Convertible Senior Notes due 2022 (Details)	1 Months Ended			6 Months Ended	12 Months Ended
	Aug. 31, 2019USD ($)	Apr. 30, 2019USD ($)$ / sharesshares	Jun. 30, 2015USD ($)D$ / sharesshares	Jun. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Apr. 15, 2019$ / shares
Notes Payable
Payments for convertible note hedges	$ 25,200,000		$ 21,100,000
Proceeds from partial termination of convertible note hedges and note hedge warrants	3,200,000
Convertible Note Hedge
Notes Payable
Conversion price (in dollars per share) | $ / shares				$ 16.58			$ 14.51
Shares issuable upon conversion of debt (in shares) | shares				20,249,665
2.25% Convertible Senior Notes due 2022 | Convertible Senior Notes
Notes Payable
Aggregate principal amount of notes issued			335,700,000	$ 120,699,000		$ 120,699,000
Net proceed received			324,000,000
Fees and expenses			$ 11,700,000
Stated interest rate (as a percent)			2.25%
Conversion rate, number of shares to be issued per		68.9172	60.3209
Principal amount used for debt instrument conversion ratio		$ 1,000	$ 1,000
Conversion price (in dollars per share) | $ / shares		$ 14.51	$ 16.58
Shares issuable upon conversion of debt (in shares) | shares		23,135,435	20,249,665
Number of trading days | D			20
Consecutive trading days | D			30
Minimum percentage of stock price			130.00%
Number of business days immediately after any five consecutive trading day period during the measurement period | D			5
Number of consecutive trading days before five business days during the measurement period | D			5
Repurchase price, as percentage of principal amount, if company undergoes change of control			100.00%
Percentage of aggregate principal amount payable, in case of event of default			25.00%
Maximum period of the sole remedy for event failures in the Indenture				180 days
Amortization period			7 years
Debt redeemed/repurchased	215,000,000
Debt redemption/repurchase price	227,300,000
Loss on extinguishment of debt					$ 23,400,000
Equity component of convertible senior notes	$ (27,000,000)
Initial debt issuance costs					$ 2,800,000
2.25% Convertible Senior Notes due 2022 | Convertible Senior Notes | Maximum
Notes Payable
Percentage of the trading price to the product of the sale price of the entity's common stock and the conversion rate			98.00%

Notes Payable - 0.75% Convertib

Notes Payable - 0.75% Convertible Senior Notes Due 2024 and 1.50% Convertible Senior Notes Due 2026 (Details)	1 Months Ended
	Aug. 31, 2019USD ($)D$ / shares	Apr. 30, 2019USD ($)$ / sharesshares	Jun. 30, 2015USD ($)D$ / sharesshares	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)
Notes Payable
Payments for convertible note hedges	$ 25,200,000		$ 21,100,000
Percentage of aggregate principal amount of notes outstanding and payable in case of event of default under the agreement	25.00%
2.25% Convertible Senior Notes due 2022 | Convertible Senior Notes
Notes Payable
Aggregate principal amount of notes issued			335,700,000	$ 120,699,000	$ 120,699,000
Net proceed received			324,000,000
Fees and expenses			$ 11,700,000
Stated interest rate (as a percent)			2.25%
Conversion rate, number of shares to be issued per		68.9172	60.3209
Principal amount used for debt instrument conversion ratio		$ 1,000	$ 1,000
Initial conversion price (in dollars per share) | $ / shares		$ 14.51	$ 16.58
Shares issuable upon conversion of debt (in shares) | shares		23,135,435	20,249,665
Number of trading days | D			20
Consecutive trading days | D			30
Minimum percentage of stock price			130.00%
Number of business days immediately after any five consecutive trading day period during the measurement period | D			5
Number of consecutive trading days before five business days during the measurement period | D			5
Repurchase price, as percentage of principal amount, if company undergoes change of control			100.00%
Percentage of aggregate principal amount payable, in case of event of default			25.00%
Amortization period			7 years
Debt instrument term			7 years
2.25% Convertible Senior Notes due 2022 | Convertible Senior Notes | Maximum
Notes Payable
Percentage of the trading price to the product of the sale price of the entity's common stock and the conversion rate			98.00%
0.75% Convertible Senior Notes due 2024 and 1.50% Convertible Senior Notes due 2026 | Convertible Senior Notes
Notes Payable
Net proceed received	$ 391,000,000
Fees and expenses	$ 9,000,000
Conversion rate, number of shares to be issued per	74.6687
Principal amount used for debt instrument conversion ratio	$ 1,000
Initial conversion price (in dollars per share) | $ / shares	$ 13.39
Number of consecutive trading days before five business days during the measurement period | D	5
Repurchase price	100.00%
0.75% Convertible Senior Notes due 2024 and 1.50% Convertible Senior Notes due 2026 | Convertible Senior Notes | Calendar quarter commencing after December 31, 2019
Notes Payable
Number of trading days | D	20
Consecutive trading days | D	30
0.75% Convertible Senior Notes due 2024 and 1.50% Convertible Senior Notes due 2026 | Convertible Senior Notes | Minimum | Calendar quarter commencing after December 31, 2019
Notes Payable
Minimum percentage of stock price	130.00%
0.75% Convertible Senior Notes due 2024 and 1.50% Convertible Senior Notes due 2026 | Convertible Senior Notes | Maximum | Measurement period
Notes Payable
Conversion premium percentage on sale price of common stock	98.00%
0.75% Convertible Senior Notes due 2024 | Convertible Senior Notes
Notes Payable
Aggregate principal amount of notes issued	$ 200,000,000			200,000,000	200,000,000
Stated interest rate (as a percent)	0.75%
Amortization period	5 years
Debt instrument term	5 years
1.50% Convertible Senior Notes due 2026 | Convertible Senior Notes
Notes Payable
Aggregate principal amount of notes issued	$ 200,000,000			$ 200,000,000	$ 200,000,000
Stated interest rate (as a percent)	1.50%
Amortization period	7 years
Debt instrument term	7 years

Notes Payable - Convertible S_2

Notes Payable - Convertible Senior Notes - Balances (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Aug. 31, 2019	Jun. 30, 2015
Liability component:
Less: unamortized debt discount	$ (72,959)	$ (83,900)
Less: unamortized debt issuance costs	(5,733)	(6,543)
Net carrying amount	442,007	430,256
Total equity component	112,309	112,309
2.25% Convertible Senior Notes due 2022
Liability component:
Total equity component	19,807	19,807
2.25% Convertible Senior Notes due 2022 | Convertible Senior Notes
Liability component:
Aggregate principal amount of notes issued	120,699	120,699		$ 335,700
0.75% Convertible Senior Notes due 2024
Liability component:
Total equity component	41,152	41,152
0.75% Convertible Senior Notes due 2024 | Convertible Senior Notes
Liability component:
Aggregate principal amount of notes issued	200,000	200,000	$ 200,000
1.50% Convertible Senior Notes due 2026
Liability component:
Total equity component	51,350	51,350
1.50% Convertible Senior Notes due 2026 | Convertible Senior Notes
Liability component:
Aggregate principal amount of notes issued	$ 200,000	$ 200,000	$ 200,000

Notes Payable - Convertible S_3

Notes Payable - Convertible Senior Notes - Additional Information (Details) - 2.25% Convertible Senior Notes due 2022 - Convertible Senior Notes - USD ($) $ in Millions	1 Months Ended
	Jun. 30, 2015	Dec. 31, 2020	Jun. 30, 2019
Notes Payable
Debt issuance costs incurred	$ 11.7
Debt issuance costs allocated to equity components	4
Debt issuance costs allocated to liability components	$ 7.7
Debt instrument term	7 years
Effective interest rate on liability components		9.90%	9.34%

Notes Payable - Convertible S_4

Notes Payable - Convertible Senior Notes - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest Expense
Contractual interest expense	$ 1,804	$ 1,802	$ 3,607	$ 3,609
Amortization of debt issuance costs	412	360	811	705
Amortization of debt discount	5,516	5,156	10,940	10,224
Total interest expense	$ 7,732	$ 7,318	$ 15,358	$ 14,538

Notes Payable - Convertible S_5

Notes Payable - Convertible Senior Notes - Future Minimum Payments (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Future minimum payments of Convertible senior notes
2021	$ 3,608
2022	126,557
2023	4,500
2024	203,750
2025	3,000
2026	201,500
Total future minimum payments under the convertible senior notes	542,915
Less: amounts representing interest	(22,216)
Less: unamortized debt discount	(72,959)	$ (83,900)
Less: unamortized debt issuance costs	(5,733)	(6,543)
Net carrying amount	442,007	$ 430,256
Long-term debt, current maturities	$ 120,700

Notes Payable - 2.25% Convertib

Notes Payable - 2.25% Convertible Senior Notes Due 2022, 0.75% Convertible Senior Notes Due 2024 and 1.50% Convertible Senior Notes Due 2026 (Details) - Convertible Senior Notes - USD ($) $ in Millions	1 Months Ended
	Aug. 31, 2019	Jun. 30, 2015	Dec. 31, 2020	Jun. 30, 2019
2.25% Convertible Senior Notes due 2022
Notes Payable
Debt issuance costs incurred		$ 11.7
Debt issuance costs allocated to equity components		4
Debt issuance costs allocated to liability components		$ 7.7
Debt instrument term		7 years
Effective interest rate on liability components			9.90%	9.34%
0.75% Convertible Senior Notes due 2024 and 1.50% Convertible Senior Notes due 2026
Notes Payable
Debt issuance costs incurred	$ 9
Debt issuance costs allocated to equity components	2.1
Debt issuance costs allocated to liability components	$ 6.9
0.75% Convertible Senior Notes due 2024
Notes Payable
Debt instrument term	5 years
Effective interest rate on liability components			6.40%
1.50% Convertible Senior Notes due 2026
Notes Payable
Debt instrument term	7 years
Effective interest rate on liability components			6.70%

Notes Payable - Convertible Not

Notes Payable - Convertible Note Hedge and Warrant Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 15, 2019	Jun. 30, 2015	Jun. 30, 2021	Dec. 31, 2020
Notes Payable
Warrants strike price (in dollars per share)	$ 18.82
Long-term asset				$ 13,065
Long-term liability			$ 11,061	$ 12,088
Net derivative issuance cost		$ 21,100
Convertible Note Hedge
Notes Payable
Shares issuable upon conversion of debt (in shares)			20,249,665
Conversion price (in dollars per share)	$ 14.51		$ 16.58
Long-term asset		91,900
Note Hedge Warrant Derivatives
Notes Payable
Shares into which warrants may be converted (in shares)			20,249,665
Trading day period			150 days
Long-term liability		$ 70,800
Note Hedge Warrants
Notes Payable
Warrants strike price (in dollars per share)			$ 21.50
Note Hedge Warrants | 2.25% Convertible Senior Notes due 2022
Notes Payable
Shares issuable upon conversion of debt (in shares)	23,135,435

Notes Payable - Capped Calls wi

Notes Payable - Capped Calls with Respect to 2024 Convertible Notes and 2026 Convertible Notes (Details) - Capped Calls with Respect to 2024 Convertible Notes and 2026 Convertible Notes $ / shares in Units, $ in Millions	1 Months Ended
	Aug. 31, 2019USD ($)$ / shares$ / itemshares
Capped Calls
Payment made to enter into Capped Calls	$ 25.2
Strike price (in dollars per share) | $ / shares	$ 13.39
Cap price | $ / item	17.05
Number of shares covered by capped calls (in shares) | shares	29,867,480
Purchase of capped calls	$ 25
Equity component of issuance costs for convertible senior notes	$ 0.2

Employee Stock Benefit Plans (D

Employee Stock Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee Stock Benefit Plans
Share-based compensation expense	$ 4,589	$ 7,091	$ 9,985	$ 13,455
Research and development
Employee Stock Benefit Plans
Share-based compensation expense	1,134	1,405	2,377	2,801
Selling, general and administrative
Employee Stock Benefit Plans
Share-based compensation expense	$ 3,455	$ 5,686	7,498	$ 10,654
Restructuring expenses
Employee Stock Benefit Plans
Share-based compensation expense			$ 110

Stock Repurchase Plan (Details)

Stock Repurchase Plan (Details) $ in Millions	1 Months Ended
	May 31, 2021USD ($)
Stock Repurchase Program
Stock repurchase program, authorized amount	$ 150
Stock repurchase program, expiration date	Dec. 31, 2022

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Expense (Benefit), Continuing Operations, by Jurisdiction [Abstract]
Income tax (benefit) expense	$ (336,931)	$ 0	$ (336,499)	$ 0

Income Taxes - Valuation Allowa

Income Taxes - Valuation Allowance (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021
Release of Valuation Allowance on Majority of Tax Attributes and Other Deferred Tax Assets [Member]
Income Taxes
(Decrease) increase in valuation allowance	$ (337.8)	$ (337.8)

Income Taxes - Federal Statutor

Income Taxes - Federal Statutory Rate (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Effective Income Tax Rate Reconciliation, Percent
Federal statutory rate (as a percent)	21.00%	21.00%	21.00%	21.00%

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Affiliated Entity | Cyclerion Therapeutics, Inc. | Research and development
Related Party Transactions
Expense for service provided by related party	$ 0.8	$ 1.8

Workforce Reduction and Restr_3

Workforce Reduction and Restructuring - General Information (Details) $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
	Sep. 30, 2020employee	Jun. 30, 2021USD ($)	Jun. 30, 2021USD ($)
Restructuring Expenses
Restructuring expenses		$ (282)	$ 29
Adjustments			$ (594)
Reduction in Workforce, Discontinued Development of IW-3718, September 29, 2020
Workforce Reduction
Number of employees eliminated | employee	100
Restructuring Expenses
Adjustments		$ (300)

Workforce Reduction and Restr_4

Workforce Reduction and Restructuring - Tabular Disclosure (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Workforce Reduction
Balance at beginning of period	$ 10,907
Charges	1,073
Amounts paid	(9,109)
Adjustments	(594)
Balance at end of period	2,277
Employee severance, benefits and related costs
Workforce Reduction
Balance at beginning of period	10,902
Charges	1,025
Amounts paid	(9,056)
Adjustments	(594)
Balance at end of period	2,277
Contract related costs
Workforce Reduction
Balance at beginning of period	5
Charges	48
Amounts paid	(53)
Balance at end of period	$ 0