PTC Therapeutics (PTCT) 10-Q 5 Aug 20 2020 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2020	Aug. 03, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-35969
Entity Registrant Name	PTC Therapeutics, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3416587
Entity Address, Address Line One	100 Corporate Court
Entity Address, City or Town	South Plainfield,
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07080
City Area Code	908
Local Phone Number	222-7000
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
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	PTCT
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		67,703,214
Entity Central Index Key	0001070081
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2

Consolidated Balance Sheets (un

Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 158,461	$ 288,028
Marketable securities	340,430	398,535
Trade receivables, net	53,644	55,538
Inventory, net	18,373	19,285
Prepaid expenses and other current assets	34,116	17,898
Total current assets	605,024	779,284
Fixed assets, net	26,806	21,549
Intangible assets, net	708,814	710,500
Goodwill	82,341	82,341
Deposits and other assets	53,652	30,108
Total assets	1,476,637	1,623,782
Current liabilities:
Accounts payable and accrued expenses	164,376	159,276
Current portion of long-term debt	18,333	20,000
Deferred revenue	7,702	8,242
Finance lease liabilities- current	4,180	0
Other current liabilities	4,868	8,339
Deferred consideration payable	2,384	40,000
Total current liabilities	201,843	235,857
Deferred revenue- long term	0	3,415
Long-term debt	297,029	293,859
Contingent consideration payable	225,700	356,300
Deferred tax liability	130,862	130,862
Finance lease liabilities- noncurrent	22,031	0
Other long-term liabilities	26,678	9,159
Total liabilities	904,143	1,029,452
Stockholders’ equity:
Common stock, $0.001 par value. Authorized 125,000,000 shares; issued and outstanding 67,240,679 shares at June 30, 2020. Authorized 125,000,000 shares; issued and outstanding 61,935,870 shares at December 31, 2019.	67	62
Additional paid-in capital	2,067,274	1,795,351
Accumulated other comprehensive income	(10,016)	(10,584)
Accumulated deficit	(1,484,831)	(1,190,499)
Total stockholders’ equity	572,494	594,330
Total liabilities and stockholders’ equity	$ 1,476,637	$ 1,623,782

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001
Common stock, authorized shares (in shares)	125,000,000	125,000,000
Common stock, issued shares (in shares)	67,240,679	61,935,870

Consolidated Statements of Oper

Consolidated Statements of Operations (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Revenue	$ 75,239	$ 85,522	$ 143,498	$ 139,105
Cost of Goods and Service, Excluding Amortization Of Intangible Assets	5,304	3,211	9,389	5,587
Operating expenses:
Amortization of acquired intangible assets	8,731	6,575	16,679	12,652
Research and development	176,525	59,979	266,632	112,544
Selling, general and administrative	53,659	49,215	111,869	89,760
Change in the fair value of deferred and contingent consideration	7,680	5,300	8,580	26,460
Settlement of deferred and contingent consideration	10,613	0	10,613	0
Total operating expenses	262,512	124,280	423,762	247,003
Loss from operations	(187,273)	(38,758)	(280,264)	(107,898)
Interest expense, net	(5,379)	(2,074)	(11,021)	(4,362)
Other income (expense), net	11,309	(183)	(2,523)	(292)
Loss before income tax expense	(181,343)	(41,015)	(293,808)	(112,552)
Income tax expense	(84)	(774)	(306)	(1,350)
Net loss attributable to common stockholders	$ (181,427)	$ (41,789)	$ (294,114)	$ (113,902)
Weighted-average shares outstanding:
Basic and diluted (in shares)	65,150,780	55,912,748	63,769,958	57,113,141
Net loss per share-basic and diluted (in dollars per share)
Net loss per share—basic and diluted (in dollars per share)	$ (2.78)	$ (0.75)	$ (4.61)	$ (1.99)
Net product revenue
Revenues:
Revenue	$ 75,239	$ 85,476	$ 143,435	$ 138,530
Collaboration and grant revenue
Revenues:
Revenue	$ 0	$ 46	$ 63	$ 575

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (181,427)	$ (41,789)	$ (294,114)	$ (113,902)
Other comprehensive (loss) income:
Unrealized gain on marketable securities, net of tax	2,718	839	2,655	898
Foreign currency translation (loss) gain, net of tax	(10,749)	278	(2,087)	(438)
Comprehensive loss	$ (189,458)	$ (40,672)	$ (293,546)	$ (113,442)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	AOCI Attributable to Parent	Accumulated deficit
Balance (in shares) at Dec. 31, 2018		50,606,147
Balance at the beginning of the period at Dec. 31, 2018	$ 350,727	$ 51	$ 1,288,137	$ 1,462	$ (938,923)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to equity offering (in shares)		7,563,725
Issuance of common stock related to equity offering	224,545	$ 7	224,538
Issuance of common stock related to rights exchange	0
Exercised (in shares)		311,002
Exercise of options	4,129	$ 0	4,129
Restricted stock vesting and issuance, net (in shares)		171,592
Restricted stock vesting and issuance, net	0
Issuance of common stock in connection with an employee stock purchase plan (in shares)		54,719
Issuance of common stock in connection with an employee stock purchase plan	1,564	$ 0	1,564
Share-based compensation expense	20,184		20,184
Receivable from investor	978		978
Net loss	(113,902)				(113,902)
Comprehensive income	460			460
Balance (in shares) at Jun. 30, 2019		58,707,185
Balance at the end of the period at Jun. 30, 2019	488,685	$ 58	1,539,530	1,922	(1,052,825)
Balance (in shares) at Mar. 31, 2019		58,418,790
Balance at the beginning of the period at Mar. 31, 2019	512,942	$ 58	1,523,115	805	(1,011,036)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to equity offering (in shares)		0
Issuance of common stock related to equity offering	106	$ 0	106
Exercised (in shares)		230,176
Exercise of options	2,847		2,847
Restricted stock vesting and issuance, net (in shares)		3,500
Restricted stock vesting and issuance, net	0
Issuance of common stock in connection with an employee stock purchase plan (in shares)		54,719
Issuance of common stock in connection with an employee stock purchase plan	1,564	$ 0	1,564
Share-based compensation expense	10,920		10,920
Receivable from investor	978		978
Net loss	(41,789)				(41,789)
Comprehensive income	1,117			1,117
Balance (in shares) at Jun. 30, 2019		58,707,185
Balance at the end of the period at Jun. 30, 2019	488,685	$ 58	1,539,530	1,922	(1,052,825)
Balance (in shares) at Dec. 31, 2019		61,935,870
Balance at the beginning of the period at Dec. 31, 2019	594,330	$ 62	1,795,351	(10,584)	(1,190,499)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to equity offering (in shares)		368,514
Issuance of common stock related to equity offering	18,950	$ 0	18,950
Payments for asset acquisitions, shares (in shares)		845,364
Payments for asset acquisitions, share, value	42,869	$ 1	42,868
Issuance of common stock related to rights exchange (in shares)		2,821,176
Issuance of common stock related to rights exchange	150,528	$ 3	150,525
Exercised (in shares)		1,034,288
Exercise of options	25,045	$ 1	25,044
Restricted stock vesting and issuance, net (in shares)		176,776
Restricted stock vesting and issuance, net	0
Issuance of common stock in connection with an employee stock purchase plan (in shares)		58,691
Issuance of common stock in connection with an employee stock purchase plan	2,406	$ 0	2,406
Share-based compensation expense	32,130		32,130
Other	(218)
Net loss	(294,114)				(294,114)
Comprehensive income	568			568
Balance (in shares) at Jun. 30, 2020		67,240,679
Balance at the end of the period at Jun. 30, 2020	572,494	$ 67	2,067,274	(10,016)	(1,484,831)
Balance (in shares) at Mar. 31, 2020		62,758,520
Balance at the beginning of the period at Mar. 31, 2020	528,734	$ 62	1,834,061	(1,985)	(1,303,404)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to equity offering (in shares)		106,309
Issuance of common stock related to equity offering	5,447	$ 0	5,447
Payments for asset acquisitions, shares (in shares)		845,364
Payments for asset acquisitions, share, value	42,869	$ 1	42,868
Issuance of common stock related to rights exchange (in shares)		2,821,176
Issuance of common stock related to rights exchange	150,528	$ 3	150,525
Exercised (in shares)		654,604
Exercise of options	15,058	$ 1	15,057
Restricted stock vesting and issuance, net (in shares)		(3,985)
Restricted stock vesting and issuance, net	0
Issuance of common stock in connection with an employee stock purchase plan (in shares)		58,691
Issuance of common stock in connection with an employee stock purchase plan	2,406	$ 0	2,406
Share-based compensation expense	16,910		16,910
Net loss	(181,427)
Comprehensive income	(8,031)			(8,031)
Balance (in shares) at Jun. 30, 2020		67,240,679
Balance at the end of the period at Jun. 30, 2020	$ 572,494	$ 67	$ 2,067,274	$ (10,016)	$ (1,484,831)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (294,114)	$ (113,902)
Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract]
Depreciation and amortization	19,445	14,760
Non-cash operating lease expense	2,401	1,256
Non-cash finance lease amortization expense	41,212	0
Change in valuation of deferred and contingent consideration	8,580	26,460
Settlement of deferred and contingent consideration	10,613	0
Non-cash stock consideration, acquisition	42,869	0
Unrealized loss on equity investment	1,600	(129)
Unrealized loss on ClearPoint convertible debt security	749	0
Non-cash interest expense	10,993	4,055
Loss on disposal of asset	26	50
Amortization of discounts on investments, net	(635)	(907)
Amortization of debt issuance costs	510	280
Amortization of discounts on investments, net	32,130	20,184
Unrealized foreign currency transaction (gains) losses, net	(3,248)	62
Increase (Decrease) in Operating Capital [Abstract]
Inventory, net	943	(852)
Prepaid expenses and other current assets	(16,569)	(7,250)
Trade receivables, net	1,860	(9,702)
Deposits and other assets	(175)	(9,656)
Accounts payable and accrued expenses	(7,497)	(7,546)
Other long-term liabilities	(4,132)	7,395
Deferred revenue	(3,925)	2,511
Net cash used in operating activities	(156,364)	(72,931)
Cash flows from investing activities
Purchases of fixed assets	(8,183)	(4,851)
Purchase of convertible debt security	(10,000)	0
Purchases of marketable securities	(367,102)	(226,261)
Sale and redemption of marketable securities	428,490	58,424
Acquisition of product rights and licenses	(2,422)	(11,981)
Purchase of equity investment	0	(4,000)
Net cash provided by (used in) investing activities	40,783	(188,669)
Cash flows from financing activities
Proceeds from exercise of options	25,045	4,129
Net proceeds from public offerings	18,950	224,545
Repayment of senior secured term loan	(10,000)	(1,667)
Payments on deferred consideration obligation	(35,829)	0
Proceeds from employee stock purchase plan	2,406	1,564
Payment of finance lease principal	(15,000)	0
Net cash provided by financing activities	(14,428)	228,571
Effect of exchange rate changes on cash	442	(375)
Net decrease in cash and cash equivalents	(129,567)	(33,404)
Cash and cash equivalents, and restricted cash beginning of period	295,528	169,498
Cash and cash equivalents, and restricted cash end of period	158,461
Supplemental disclosure of cash information
Cash paid for interest	5,286	3,111
Cash paid for income taxes	1,140	1,013
Supplemental disclosure of non-cash investing and financing activity
Unrealized gain on marketable securities, net of tax	2,655	898
Right-of-use assets obtained in exchange for operating lease obligations	18,117	11,643
Right-of-use assets obtained in exchange for finance lease obligations	41,212	0
Acquisition of product rights and licenses	12,186	8,269
Issuance of common stock related to rights exchange	$ 150,528	$ 0

The Company

The Company	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	The Company PTC Therapeutics, Inc. (the “Company” or “PTC”) is a science-driven global biopharmaceutical company focused on the discovery, development and commercialization of clinically-differentiated medicines that provide benefits to patients with rare disorders. The Company’s ability to globally commercialize products is the foundation that drives its continued investment in a robust diversified pipeline of transformative medicines and its mission to provide access to best-in-class treatments for patients who have an unmet medical need. The Company’s strategy is to bring best-in-class therapies with differentiated clinical benefit to patients affected by rare disorders and to leverage its global commercial infrastructure to maximize value for its patients and other stakeholders. The Company has two products, Translarna ™ (ataluren) and Emflaza™ (deflazacort), for the treatment of Duchenne muscular dystrophy, or DMD, a rare, life threatening disorder. Translarna has marketing authorization in the European Economic Area (the “EEA”) for the treatment of nonsense mutation Duchenne muscular dystrophy, or nmDMD, in ambulatory patients aged 2 years and older and in Brazil for the treatment of nmDMD in ambulatory patients aged 5 years and older, subject to annual renewal and other conditions. In June 2020, the Committee for Medicinal Products for Human Use (the "CHMP") of the European Medicines Agency ("EMA") recommended to remove the statement “efficacy has not been demonstrated in non-ambulatory patients” from the product label for Translarna. The CHMP's opinion is subject to final approval by the European Commission, which is typically provided within two months of the CHMP's recommendation. Emflaza is approved in the United States for the treatment of DMD in patients two years and older. The Company has a pipeline of gene therapy product candidates for rare monogenic diseases that affect the central nervous system (“CNS”) including PTC-AADC for the treatment of Aromatic L-Amino Acid Decarboxylase, or AADC deficiency, a rare CNS disorder arising from reductions in the enzyme AADC that results from mutations in the dopa decarboxylase gene. The Company is preparing a biologics license application ("BLA") for PTC-AADC for the treatment of AADC deficiency in the United States and it anticipates initiating the BLA submission to the United States Food and Drug Administration ("FDA") in the second half of 2020. In January 2020, the Company submitted a marketing authorization application ("MAA") to the EMA for PTC-AADC for the treatment of AADC deficiency in the EEA, and the Company expects an opinion from the CHMP in the first quarter of 2021. The Company holds the rights for the commercialization of Tegsedi™ (inotersen) and Waylivra™ (volanesorsen) for the treatment of rare diseases in countries in Latin America and the Caribbean pursuant to the Company’s Collaboration and License Agreement with Akcea Therapeutics, Inc. (“Akcea”). Tegsedi has received marketing authorization in the United States, the European Union (the “EU”) and Brazil for the treatment of stage 1 or stage 2 polyneuropathy in adult patients with hereditary transthyretin amyloidosis, or hATTR amyloidosis. Waylivra has received marketing authorization in the EU for the treatment of familial chylomicronemia syndrome, or FCS. The Company filed for marketing authorization for Waylivra for the treatment of FCS with ANVISA, the Brazilian health regulatory authority, in June 2020 and, subject to potential delays in the review process related to the COVID-19 pandemic, expects a regulatory decision on approval from ANVISA in 2021. The Company also has a spinal muscular atrophy ("SMA") collaboration with F. Hoffman-La Roche Ltd and Hoffman-La Roche Inc., referred to collectively as Roche, and the Spinal Muscular Atrophy Foundation ("SMA Foundation"). The lead compound in the SMA program is risdiplam (RG7916, RO7034067). Roche submitted an NDA for risdiplam to the FDA in the fourth quarter of 2019. In April 2020, the FDA extended the Prescription Drug User Fee Act ("PDUFA") date for a decision from May 24, 2020 to August 24, 2020 as a result of additional data that Roche submitted, including comprehensive data from the Sunfish part 2 study. Risdiplam is expected to be indicated in the United States for SMA type 1, 2 and 3 patients, if approved. Roche anticipates submitting an MAA for risdiplam in the EEA imminently. On October 25, 2019, the Company completed the acquisition of substantially all of the assets of BioElectron Technology Corporation (“BioElectron”), a Delaware corporation, including certain compounds that the Company has begun to develop as part of its Bio-e platform, (the “Asset Acquisition”) pursuant to an asset purchase agreement by and between the Company and BioElectron, dated October 1, 2019 (the “Asset Acquisition Agreement”). The transaction was accounted for as an asset acquisition. The two most advanced molecules in the Company's Bio-e platform are vatiquinone, formerly known as PTC743, and PTC857. The Company expects to initiate a potential registrational Phase 2 placebo-controlled trial of vatiquinone in approximately 60 children with mitochondrial disease and associated refractory epilepsy in the third quarter of 2020. The Company also expects to initiate a potential registrational Phase 3 trial of vatiquinone in approximately 100 patients with Friedrich ataxia in the fourth quarter of 2020. In the second quarter of 2020, the Company initiated a Phase 1 trial in healthy volunteers to evaluate the safety and pharmacology of PTC857. The Company expects data from the single ascending dose and multiple ascending dose studies from the Phase 1 trial to be available by the end of 2020. In addition, the Company has a pipeline of product candidates and discovery programs that are in early clinical, pre-clinical and research and development stages focused on the development of new treatments for multiple therapeutic areas, including rare diseases and oncology. The Company’s marketing authorization for Translarna in the EEA is subject to annual review and renewal by the European Commission following reassessment by the EMA of the benefit-risk balance of the authorization, which the Company refers to as the annual EMA reassessment. This marketing authorization is further subject to the specific obligation to conduct and submit the results of a multi-center, randomized, double-blind, 18-month, placebo-controlled trial, followed by an 18-month open-label extension, according to an agreed protocol, in order to confirm the efficacy and safety of Translarna. The final report on the trial and open-label extension is to be submitted by the Company to the EMA by the end of the third quarter of 2022. The Company refers to the trial and open-label extension together as Study 041. The marketing authorization in the EEA was last renewed in June 2020 and is effective, unless extended, through August 5, 2021. The renewal was based on the Company’s commitment to conduct Study 041 and the totality of the clinical data available from its trials and studies of Translarna for the treatment of nmDMD, including the safety and efficacy results of the Phase 2b and Phase 3 clinical trials. The primary efficacy endpoint was not achieved in either trial within the pre-specified level of statistical significance. Translarna is an investigational new drug in the United States. During the first quarter of 2017, the Company filed a New Drug Application, or NDA, over protest with the FDA, for which the FDA granted a standard review. In October 2017, the Office of Drug Evaluation I of the FDA issued a complete response letter for the NDA, stating that it was unable to approve the application in its current form. In response, the Company filed a formal dispute resolution request with the Office of New Drugs of the FDA. In February 2018, the Office of New Drugs of the FDA denied the Company's appeal of the Complete Response Letter. In its response, the Office of New Drugs recommended a possible path forward for the ataluren NDA submission based on the accelerated approval pathway. This would involve a re-submission of an NDA containing the current data on effectiveness of ataluren with new data to be generated on dystrophin production in nmDMD patients’ muscles. The Company intends to follow the FDA’s recommendation and will collect, using newer technologies via procedures and methods that the Company designed, such dystrophin data in a new study, Study 045, which the Company initiated in the fourth quarter of 2018. As a result of intermittent discontinuations of certain elective procedures at the Company's clinical trial site in response to the COVID-19 pandemic, the Company's expected completion of Study 45 has been delayed as certain patients still require final study muscle biopsies. Once the clinical trial site is open for the necessary procedures and patients are able to safely travel to the site, the Company expects to be able to complete the final biopsies and the data from Study 045 would be available thereafter, followed by a potential re-submission of an NDA. Additionally, should a re-submission of an NDA receive accelerated approval, the Office of New Drugs stated that Study 041, which is currently enrolling, could serve as the confirmatory post-approval trial required in connection with the accelerated approval framework. On August 23, 2018, the Company completed its acquisition of Agilis Biotherapeutics, Inc., or Agilis, pursuant to an Agreement and Plan of Merger, dated as of July 19, 2018 (the “Merger Agreement”), by and among the Company, Agility Merger Sub, Inc., a Delaware corporation and the Company's wholly owned, indirect subsidiary, Agilis and, solely in its capacity as the representative, agent and attorney-in-fact of the equityholders of Agilis, Shareholder Representative Services LLC, (the "Merger"). Upon the closing of the Merger, the Company paid to Agilis equityholders total upfront consideration comprised of $49.2 million in cash and 3,500,907 shares of the Company’s common stock (the “Closing Stock Consideration”). The Closing Stock Consideration was determined by dividing $150.0 million by the volume-weighted average price per share of the Company’s common stock on the Nasdaq Global Select Market for the 10 consecutive trading-day period ending on the second trading-day immediately preceding the closing of the Merger. Agilis equityholders are entitled to receive contingent payments from the Company based on the achievement of certain development, regulatory and net sales milestones as well as based upon a percentage of net sales of certain products. On April 29, 2020, the Company, certain of the former equity holders of Agilis, and, for the limited purposes set forth in the agreement, Shareholder Representative Services LLC, entered into a Rights Exchange Agreement (the “Rights Exchange Agreement”). Pursuant to the Rights Exchange Agreement, the Company issued 2,821,176 shares of its common stock (the “Common Stock Consideration”) and paid $36.9 million (the “Cash Consideration”), in the aggregate, to such former equity holders of Agilis (the “Participating Rightholders”) in exchange for the cancellation and forfeiture by the Participating Rightholders of their rights to receive certain milestone-based contingent payments under the Merger Agreement, pursuant to which the Company completed the Merger. Pursuant to the terms of the Rights Exchange Agreement, the Participating Rightholders have canceled and forfeited their rights under the Merger Agreement to receive (i) $174.0 million, in the aggregate, of potential milestone payments based on the achievement of certain regulatory milestones and (ii) $37.6 million, in the aggregate, of $40.0 million in development milestone payments that would have been due upon the passing of the second anniversary of the closing of the Merger, regardless of whether the milestones are achieved. The Rights Exchange Agreement has no effect on the Merger Agreement other than to provide for the cancellation and forfeiture of the Participating Rightholders’ rights to receive $211.6 million, in the aggregate, of the milestone payments described above. As a result, all other rights and obligations under the Merger Agreement remain in effect pursuant to their terms, including the Company’s obligation to pay up to an aggregate maximum amount of $22.4 million upon the achievement of certain development milestones (representing the remaining portion of potential development milestone payments for which rights were not canceled and forfeited pursuant to the Rights Exchange Agreement after deducting the $37.6 million for which rights were canceled and forfeited pursuant to the Rights Exchange Agreement from the $40.0 million in development milestone payments that are due upon the passing of the second anniversary of the closing of the Merger), up to an aggregate maximum amount of $361.0 million upon the achievement of certain regulatory milestones (representing the remaining portion of potential regulatory milestone payments for which rights were not canceled and forfeited pursuant to the Rights Exchange Agreement), up to a maximum aggregate amount of $150.0 million upon the achievement of certain net sales milestones and a percentage of annual net sales for Friedreich ataxia and Angelman syndrome during specified terms, ranging from 2% to 6%, pursuant to the terms of the Merger Agreement. Refer to Note 5 for further details regarding the Rights Exchange Agreement. On May 29, 2020, the Company completed its acquisition of Censa Pharmaceuticals, Inc., (“Censa”) pursuant to an Agreement and Plan of Merger, dated as of May 5, 2020, (the "Censa Merger Agreement"), by and among the Company, Hydro Merger Sub, Inc., the Company's wholly owned, indirect subsidiary, and, solely in its capacity as the representative, agent and attorney-in-fact of the securityholders of Censa, Shareholder Representative Services LLC (the "Censa Merger"). The transaction was accounted for as an asset acquisition. In connection with the Censa Merger, the Company acquired PTC923 (formerly known as CNSA-001), which is being pursued as a possible treatment for orphan metabolic diseases associated with defects in the tetrahydrobiopterin biochemical pathways, including phenylketonuria ("PKU"). Refer to Note 3 for further details. As of June 30, 2020, the Company had an accumulated deficit of approximately $1,484.8 million. The Company has financed its operations to date primarily through the private offerings in September 2019 of 1.50% convertible senior notes due 2026 and in August 2015 of 3.00% convertible senior notes due 2022 (see Note 11), public offerings of common stock in February 2014, October 2014, April 2018, January 2019, and September 2019, "at the market offerings" of its common stock, its initial public offering of common stock in June 2013, private placements of its convertible preferred stock, collaborations, bank debt, the Company's credit and security agreement (the "Credit Agreement"), with MidCap Financial Trust, or MidCap Financial, as administrative agent and MidCap Financial and other certain institutions as lenders thereto (see Note 11), grant funding and clinical trial support from governmental and philanthropic organizations and patient advocacy groups in the disease area addressed by the Company’s product candidates. Since 2014, the Company has also relied on revenue generated from net sales of Translarna for the treatment of nmDMD in territories outside of the United States, and since May 2017, the Company has generated revenue from net sales of Emflaza for the treatment of DMD in the United States. The Company expects that cash flows from the sales of its products, together with the Company's cash, cash equivalents and marketable securities, will be sufficient to fund its operations for at least the next twelve months.

Summary of significant accounti

Summary of significant accounting policies	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Summary of significant accounting policies	Summary of significant accounting policies The Company’s complete listing of significant accounting policies is set forth in Note 2 of the notes to the Company’s audited financial statements as of December 31, 2019 included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (the "SEC") on March 2, 2020 (the "2019 Form 10-K"). Additional significant accounting policies adopted during the six month period ended June 30, 2020 are discussed in further detail below. Basis of presentation The accompanying financial information as of June 30, 2020 and for the three and six months ended June 30, 2020 and 2019 has been prepared by the Company, without audit, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States ("GAAP") have been condensed or omitted pursuant to such rules and regulations. These interim financial statements should be read in conjunction with the Company’s audited financial statements as of December 31, 2019 and notes thereto included in the 2019 Form 10-K. In the opinion of management, the unaudited financial information as of June 30, 2020 and for the three and six months ended June 30, 2020 and 2019 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement of financial position, results of operations, stockholders' equity, and cash flows. The results of operations for the three and six month period ended June 30, 2020 are not necessarily indicative of the results to be expected for the year ended December 31, 2020 or for any other interim period or for any other future year. Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates in these consolidated financial statements have been made in connection with the calculation of net product sales, certain accruals related to the Company’s research and development expenses, valuation procedures for convertible notes, fair value of the contingent consideration, and the provision for or benefit from income taxes. Actual results could differ from those estimates. Changes in estimates are reflected in reported results in the period in which they become known. Restricted cash Restricted cash included in deposits and other assets on the consolidated balance sheet relates to an unconditional, irrevocable and transferable letter of credit that was entered into during the twelve-month period ended December 31, 2019 in connection with obligations under a facility lease for our leased biologics manufacturing facility in Hopewell Township, New Jersey. The amount of the letter of credit is $7.5 million, is to be maintained for a term of not less than five years and has the potential to be reduced to $3.8 million if after five years the Company is not in default of its lease. The amount is classified within deposits and other assets on the consolidated balance sheet due to the long-term nature of the letter of credit. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheet that sum to the total of the same amounts shown in the statement of cash flows: Beginning of period- December 31, 2019 End of period- June 30, 2020 Cash and cash equivalents $ 288,028 $ 158,461 Restricted cash included in deposits and other assets 7,500 7,500 Total Cash, cash equivalents and restricted cash per statement of cash flows $ 295,528 $ 165,961 Marketable securities The Company considers securities with original maturities of greater than 90 days to be available for sale securities. Securities under this classification are recorded at fair value and unrealized gains and losses within accumulated other comprehensive income. The estimated fair value of the available for sale securities is determined based on quoted market prices or rates for similar instruments. In addition, the cost of debt securities in this category is adjusted for amortization of premium and accretion of discount to maturity. For available for sale debt securities in an unrealized loss position, the Company assesses whether it intends to sell or if it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security's amortized cost basis is written down to fair value. If the criteria are not met, the Company evaluates whether the decline in fair value has resulted from a credit loss or other factors. In making this assessment, management considers, among other factors, the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of the cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded for the credit loss, limited by the amount that the fair value is less than the amortized costs basis. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income. For the three month and six month periods ended June 30, 2020, no allowance was recorded for credit losses. Inventory and cost of product sales Inventory Inventories are stated at the lower of cost and net realizable value with cost determined on a first-in, first-out basis by product. The Company capitalizes inventory costs associated with products following regulatory approval when future commercialization is considered probable and the future economic benefit is expected to be realized. Products which may be used in clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes. Inventory used for marketing efforts are charged to selling, general and administrative expense. Amounts related to clinical development programs and marketing efforts are immaterial. The following table summarizes the components of the Company’s inventory for the periods indicated: June 30, 2020 December 31, 2019 Raw materials $ 877 $ 874 Work in progress 8,666 9,652 Finished goods 8,830 8,759 Total inventory $ 18,373 $ 19,285 The Company periodically reviews its inventories for excess amounts or obsolescence and writes down obsolete or otherwise unmarketable inventory to its estimated net realizable value. For the three months ended June 30, 2020, inventory write downs were immaterial. For the six months ended June 30, 2020, the Company recorded a $0.2 million inventory write-down, primarily related to product approaching expiration. No write downs were recorded for the three and six month periods ended June 30, 2019. Additionally, though the Company’s product is subject to strict quality control and monitoring which it performs throughout the manufacturing processes, certain batches or units of product may not meet quality specifications resulting in a charge to cost of product sales. For the three and six month periods ended June 30, 2020 and 2019, these amounts were immaterial. Cost of product sales Cost of product sales consists of the cost of inventory sold, manufacturing and supply chain costs, storage costs, amortization of the acquired intangible asset and royalty payments associated with net product sales. Production costs are expensed as cost of product sales when the related products are sold. Revenue recognition Net product revenue The Company's net product revenue primarily consists of sales of Translarna in territories outside of the U.S. for the treatment of nmDMD and sales of Emflaza in the U.S. for the treatment of DMD. The Company recognizes revenue when its performance obligations with its customers have been satisfied. The Company’s performance obligations are to provide products based on customer orders from distributors, hospitals, specialty pharmacies or retail pharmacies. The performance obligations are satisfied at a point in time when the Company’s customer obtains control of the product, which is typically upon delivery. The Company invoices its customers after the products have been delivered and invoice payments are generally due within 30 to 90 days of the invoice date. The Company determines the transaction price based on fixed consideration in its contractual agreements. Contract liabilities arise in certain circumstances when consideration is due for goods the Company has yet to provide. As the Company has identified only one distinct performance obligation, the transaction price is allocated entirely to product sales. In determining the transaction price, a significant financing component does not exist since the timing from when the Company delivers product to when the customers pay for the product is typically less than one year. Customers in certain countries pay in advance of product delivery. In those instances, payment and delivery typically occur in the same month. The Company records product sales net of any variable consideration, which includes discounts, allowances, rebates related to Medicaid and other government pricing programs, and distribution fees. The Company uses the expected value or most likely amount method when estimating its variable consideration, unless discount or rebate terms are specified within contracts. The identified variable consideration is recorded as a reduction of revenue at the time revenues from product sales are recognized. These estimates for variable consideration are adjusted to reflect known changes in factors and may impact such estimates in the quarter those changes are known. Revenue recognized does not include amounts of variable consideration that are constrained. For the three months ended June 30, 2020 and 2019, net product sales outside of the United States were $39.0 million and $57.8 million, respectively, and net product sales in the United States were $36.2 million and $27.6 million, respectively. For the six months ended June 30, 2020 and 2019, net product sales outside of the United States were $79.8 million and $93.0 million, respectively, and net product sales in the United States were $63.6 million and $45.4 million, respectively. In relation to customer contracts, the Company incurs costs to fulfill a contract but does not incur costs to obtain a contract. These costs to fulfill a contract do not meet the criteria for capitalization and are expensed as incurred. The Company considers any shipping and handling costs that are incurred after the customer has obtained control of the product as a cost to fulfill a promise. Shipping and handling costs associated with finished goods delivered to customers are recorded as a selling expense. Collaboration revenue The terms of these agreements typically include payments to the Company of one or more of the following: nonrefundable, upfront license fees; milestone payments; research funding and royalties on future product sales. In addition, the Company generates service revenue through agreements that generally provide for fees for research and development services and may include additional payments upon achievement of specified events. At the inception of a collaboration arrangement, the Company needs to first evaluate if the arrangement meets the criteria in ASC Topic 808 “Collaborative Arrangements” to then determine if ASC Topic 606 is applicable by considering whether the collaborator meets the definition of a customer. If the criteria are met, the Company assesses the promises in the arrangement to identify distinct performance obligations. For licenses of intellectual property, the Company assesses, at contract inception, whether the intellectual property is distinct from other performance obligations identified in the arrangement. If the licensing of intellectual property is determined to be distinct, revenue is recognized for nonrefundable, upfront license fees when the license is transferred to the customer and the customer can use and benefit from the license. If the licensing of intellectual property is determined not to be distinct, then the license will be bundled with other promises in the arrangement into one distinct performance obligation. The Company needs to determine if the bundled performance obligation is satisfied over time or at a point in time. If the Company concludes that the nonrefundable, upfront license fees will be recognized over time, the Company will need to assess the appropriate method of measuring proportional performance. For milestone payments, the Company assesses, at contract inception, whether the development or sales-based milestones are considered probable of being achieved. If it is probable that a significant revenue reversal will occur, the Company will not record revenue until the uncertainty has been resolved. Milestone payments that are contingent upon regulatory approval are not considered probable of being achieved until the applicable regulatory approvals or other external conditions are obtained as such conditions are not within the Company's control. If it is probable that a significant revenue reversal will not occur, the Company will estimate the milestone payments using the most likely amount method. The Company will re-assess the development and sales-based milestones each reporting period to determine the probability of achievement. The Company recognizes revenue for reimbursements of research and development costs under collaboration agreements as the services are performed. The Company records these reimbursements as revenue and not as a reduction of research and development expenses as the Company has the risks and rewards as the principal in the research and development activities. Allowance for doubtful accounts The Company maintains an allowance for estimated losses resulting from the inability of its customers to make required payments. The Company estimates uncollectible amounts based upon current customer receivable balances, the age of customer receivable balances, the customer’s financial condition and current economic trends. The allowance for doubtful accounts was $0.2 million as of June 30, 2020 and $0.3 million as of December 31, 2019. Bad debt expense was immaterial for the three and six month periods ended June 30, 2020 and 2019. For the three and six month periods ended June 30, 2020, no allowances were recorded for credit losses. Indefinite-lived intangible assets Indefinite-lived intangible assets consist of in process research and development ("IPR&D"). IPR&D acquired directly in a transaction other than a business combination is capitalized if the projects will be further developed or have an alternative future use; otherwise they are expensed. The fair values of IPR&D projects and license agreement assets acquired in business combinations are capitalized. Several methods may be used to determine the estimated fair value of the IPR&D and license agreement asset acquired in a business combination. The Company utilizes the "income method” and uses estimated future net cash flows that are derived from projected sales revenues and estimated costs. These projections are based on factors such as relevant market size, patent protection, and expected pricing and industry trends. The estimated future net cash flows are then discounted to the present value using an appropriate discount rate. These assets are treated as indefinite-lived intangible assets until completion or abandonment of the projects, at which time the assets are amortized over the remaining useful life or written off, as appropriate. Intangible assets with indefinite lives, including IPR&D, are tested for impairment if impairment indicators arise and, at a minimum, annually. However, an entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that an indefinite-lived intangible asset’s fair value is less than its carrying amount. Otherwise, no further impairment testing is required. The indefinite-lived intangible asset impairment test consists of a one-step analysis that compares the fair value of the intangible asset with its carrying amount. If the carrying amount of an intangible asset exceeds its fair value, an impairment loss is recognized in an amount equal to that excess. The Company considers many factors in evaluating whether the value of its intangible assets with indefinite lives may not be recoverable, including, but not limited to, expected growth rates, the cost of equity and debt capital, general economic conditions, the Company's outlook and market performance of the Company's industry and recent and forecasted financial performance. Goodwill Goodwill represents the amount of consideration paid in excess of the fair value of net assets acquired as a result of the Company’s business acquisitions accounted for using the acquisition method of accounting. Goodwill is not amortized and is subject to impairment testing at a reporting unit level on an annual basis or when a triggering event occurs that may indicate the carrying value of the goodwill is impaired. The Company reassess its reporting units as part of its annual segment review. An entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that the fair value of the reporting unit is less than its carrying amount. Income Taxes O n March 27, 2020, the United States enacted the Coronavirus Aid, Relief, and Economic Security Act, referred to herein as the CARES Act, as a response to the economic uncertainty resulting from a strain of novel coronavirus, COVID-19. The CARES Act includes modifications for net operating loss carryovers and carrybacks, limitations of business interest expense for tax, immediate refund of alternative minimum tax (AMT) credit carryovers as well as a technical correction to the 2017 Tax Cuts and Jobs Act ("the 2017 Tax Act"), referred to herein as the U.S. Tax Act, for qualified improvement property. As of June 30, 2020, the Company expects that these provisions will not have a material impact. Tax provisions of the Act also include the deferral of certain payroll taxes, relief for retaining employees, and other provisions. The Company is evaluating the impact of the Act and currently expects to benefit from the deferral of certain payroll taxes and retention credit through the end of calendar year 2020. The ultimate impact of the CARES Act may differ from this estimate due to changes in interpretations and guidance that may be issued and actions the Company may take in response to the CARES Act. The Company will continue to assess the impact that various provisions will have on its business. On December 22, 2017, the U.S. government enacted the 2017 Tax Act, which significantly revises U.S. tax law by, among other provisions, lowering the U.S. federal statutory income tax rate to 21%, imposing a mandatory one-time transition tax on previously deferred foreign earnings, and eliminating or reducing certain income tax deductions. The Global Intangible Low-tax Income ("GILTI") provisions of the 2017 Tax Act require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. The Company has elected to account for GILTI tax in the period in which it is incurred, and therefore has not provided any deferred tax impacts of GILTI in its consolidated financial statements for the period ended June 30, 2020. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and net operating loss and credit carryforwards. Deferred tax assets and liabilities are measured at rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the statement of operations in the period that includes the enactment date. A valuation allowance is recorded when it is not more likely than not that all or a portion of the net deferred tax assets will be realized. The Company recorded a deferred tax liability in conjunction with the Merger of $122.0 million related to the tax basis difference in the IPR&D indefinite-lived intangibles acquired. The Company's policy is to record a deferred tax liability related to acquired IPR&D which may eventually be realized either upon amortization of the asset when the research is completed and a product is successfully launched or the write-off of the asset if it is abandoned or unsuccessful. Leases The Company determines if an arrangement is a lease at inception. This determination generally depends on whether the arrangement conveys to the Company the right to control the use of an explicitly or implicitly identified fixed asset for a period of time in exchange for consideration. Control of an underlying asset is conveyed to the Company if the Company obtains the rights to direct the use of and to obtain substantially all of the economic benefits from using the underlying asset. The Company has lease agreements which include lease and non-lease components, which the Company accounts for as a single lease component for all leases. Operating and finance leases are classified as right of use ("ROU") assets, short term lease liabilities, and long term lease liabilities. Operating and finance lease ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. ROU assets are amortized and lease liabilities accrete to yield straight-line expense over the term of the lease. Lease payments included in the measurement of the lease liability are comprised of fixed payments. Variable lease payments associated with the Company’s leases are recognized when the event, activity, or circumstance in the lease agreement on which those payments are assessed occurs. Variable lease payments are presented in the Company’s consolidated statements of operations in the same line item as expense arising from fixed lease payments for operating leases. Leases with an initial term of 12 months or less are not recorded on the consolidated balance sheet and the Company recognizes lease expense for these leases on a straight-line basis over the lease term. The Company applies this policy to all underlying asset categories. A lessee is required to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The Company gives consideration to its recent debt issuances as well as publicly available data for instruments with similar characteristics when calculating its incremental borrowing rates. The lease term for all of the Company’s leases includes the non-cancellable period of the lease plus any additional periods covered by either a Company option to extend (or not to terminate) the lease that the Company is reasonably certain to exercise, or an option to extend (or not to terminate) the lease controlled by the lessor. Leasehold improvements are capitalized and depreciated over the lesser of useful life or lease term. See Note 4 Leases for additional information. Impact of recently adopted accounting pronouncements In December 2019, the FASB issued ASU 2019-12,"Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”. ASU 2019-12 simplifies the accounting for income taxes by removing certain exceptions to the general principals in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending the existing guidance. For public business entities, the guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2020. For all other entities, it is effective for annual periods beginning after December 15, 2021 and interim periods in annual periods beginning after December 15, 2022. Early adoption is permitted, including adoption in any interim period. The Company early adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements and accompanying notes. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments”. This standard requires financial assets measured at amortized cost basis to be presented at the net amount expected to be collected. This standard is effective for public companies who are SEC filers for fiscal years beginning after December 15, 2019, including interim periods within those years. In November 2019, the FASB issued ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, which expands the scope of the practical expedient that allows entities to exclude the accrued interest component of amortized cost from various disclosures required by ASC 326 to also include certain disclosures required by ASC 320. Entities that elect to apply the practical expedient must disclose the total amount of accrued interest that they exclude from their disclosures of amortized cost. The amendments have the same effective dates as ASU 2016-13 (Topic 326) for entities that have not yet adopted that standard. The Company adopted ASU 2016-13 and ASU 2019-11 effective January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements. The Company has updated its accounting policy for marketable securities within this footnote as well as its fair value footnote (Note 5) with additional disclosures as required by the standard upon adoption. In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement (Topic 820), Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement". This standard eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information and modifies some disclosure requirements. The new guidance is effective for all entities for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. An entity is permitted to early adopt either the entire standard or only the provisions that eliminate or modify requirements. Entities can elect to early adopt in interim periods, including periods for which they have not yet issued financial statements or made their financial statements available for issuance. The Company adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements. The Company has updated its fair value footnote (Note 5) with additional and modified disclosures as required by the standard upon adoption. In August 2018, the FASB issued ASU 2018-15,"Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract". ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and recognize as an asset. For public business entities, the guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2019. For all other entities, it is effective for annual periods beginning after December 15, 2020 and interim periods in annual periods beginning after December 15, 2021. Early adoption is permitted, including adoption in any interim period for all entities. The Company adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements and accompanying notes. In November 2018, the FASB issued ASU 2018-18,"Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606”. ASU 2018-18 provides guidance on whether certain transactions between collaborative arrangement participants should be accounted for with revenue under Topic 606. For public business entities, the guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2019. For all other entities, it is effective for annual periods beginning after December 15, 2020 and interim periods in annual periods beginning after December 15, 2021. Early adoption is permitted, including adoption in any interim period for all entities. The Company adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements and accompanying notes.

Leases

Leases	6 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Leases	LeasesThe Company leases office space in South Plainfield, New Jersey for its principal office under three noncancelable operating leases through May 2022 and August 2024, in addition to office space in various countries for international employees primarily through workspace providers. The Company also leases certain vehicles, lab equipment, and office equipment under operating leases. The Company’s leases have remaining operating lease terms ranging from 0.3 years to 6.9 years and certain of the leases include renewal options to extend the lease for up to 10 years. Rent expense was approximately $2.6 million, $5.0 million, $1.1 million and $2.1 million for the three and six month periods ended June 30, 2020 and 2019, respectively. On June 19, 2020, the Company entered into a commercial manufacturing service agreement for a term of 12.5 years with MassBiologics of the University of Massachusetts Medical School ("MassBio"). The agreement will expire on December 31, 2032 unless the Company terminates it on 24 months prior written notice to MassBio. Pursuant to the terms of the agreement, MassBio agreed to provide the Company with four dedicated rooms for its gene therapy AADC program. The Company concluded that the agreement contains an embedded lease as the Company controls the use of the four dedicated rooms and the equipment therein. As the present value of the facilities exceeds the assessed fair value, the Company determined that it is a finance lease. Given that the embedded finance lease is designed for the production of PTC’s AADC program and would not have an alternate use outside the PTC gene therapy platform without incurring significant costs, the Company determined that the lease should be treated as research and development expense under ASC 730 and accordingly, expensed the present value of all g uaranteed future cash payments of $41.2 million during the three and six month periods ending June 30, 2020. Additionally, during the three and six month periods ending June 30, 2020, the Company did not record finance lease costs as these amounts were not material due to timing of entering into the lease. The Company will record finance lease costs in the third quarter of 2020. The components of operating lease expense were as follows: Three Months Ended June 30, 2020 Three Months Ended June 30, 2019 Six Months Ended June 30, 2020 Six Months Ended June 30, 2019 Operating Lease Cost Fixed lease cost $ 1,970 $ 835 $ 4,089 $ 1,647 Variable lease cost 507 161 734 304 Short-term lease cost 88 88 165 141 Total operating lease cost $ 2,565 $ 1,084 $ 4,988 $ 2,092 Total operating lease cost is a component of operating expenses on the consolidated statements of operations. Supplemental balance sheet information related to leases was as follows: June 30, 2020 December 31, 2019 Operating lease ROU asset $ 29,475 $ 13,693 Operating lease liabilities- current $ 4,868 $ 5,153 Operating lease liabilities- noncurrent 25,510 9,018 Total operating lease liability $ 30,378 $ 14,171 June 30, 2020 December 31, 2019 Finance lease liabilities- current $ 4,180 $ — Finance lease liabilities- noncurrent 22,031 — Total finance lease liability $ 26,211 $ — Operating lease ROU asset is a component of deposits and other assets on the consolidated balance sheets. The current portion of operating lease liabilities is a component of other current liabilities on the consolidated balance sheets. The long term portion of operating lease liabilities is a component of other long term liabilities on the consolidated balance sheets. The Company entered into a lease agreement with COE Bridgewater LLC on March 20, 2020 relating to the lease of office and laboratory space located in Bridgewater, New Jersey. This lease replaced the Company's existing lease on the property beginning on May 1, 2020 and includes additional rental property of approximately 59,000 square feet and is the primary driver of the increase in total operating lease ROU asset and total operating lease liability from December 31, 2029 to June 30, 2020. Supplemental lease term and discount rate information related to leases was as follows as of June 30, 2020 and 2019: June 30, 2020 December 31, 2019 Weighted-average remaining lease terms - operating leases (years) 5.87 3.38 Weighted-average discount rate - operating leases 6.77 % 7.33 % Weighted-average remaining lease terms - finance lease (years) 12.50 — Weighted-average discount rate - finance lease 7.80 % — Supplemental cash flow information related to leases was as follows as of June 30, 2020 and 2019: Six Month Ended June 30, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3,414 $ 1,508 Financing cash flows from finance lease 15,000 — Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 18,117 $ 11,643 Finance lease 41,212 — Future minimum lease payments under non-cancelable leases as of June 30, 2020 were as follows: Operating Leases Finance Lease 2020 (excludes the six months ended June 30, 2020) $ 3,719 $ 3,000 2021 6,667 3,000 2022 6,314 3,000 2023 5,960 3,000 2024 and thereafter 14,844 27,000 Total lease payments 37,504 39,000 Less: Imputed Interest expense 7,126 12,789 Total $ 30,378 $ 26,211 In conjunction with the Asset Acquisition, the Company acquired BioElectron’s lease in Mountainview, California. As substantially all of the fair value of the gross assets acquired was related to vatiquinone, the relative fair value allocated to the right of use asset and corresponding lease liability for the Mountainview lease was determined to be immaterial, and accordingly is not included in the tables above. The future minimum lease payments for the Mountainview lease as of June 30, 2020 are $0.9 million, $1.8 million, and $1.4 million for 2020, 2021 and 2022, respectively. On August 4, 2019, the Company and Bristol-Myers Squibb Company, (the “Landlord”), entered into a Lease Agreement (the “Lease”), relating to the lease of approximately 185,000 square feet of office, manufacturing and laboratory space at a facility located in Hopewell Township, New Jersey (the “Campus”). On March 25, 2020, the Company entered into an amendment increasing the rented space to approximately 220,500 square feet. As of June 30, 2020, the Lease had not yet commenced, and accordingly, is not reflected in the table above. The rental term of the Lease commenced on July 1, 2020 and has an initial term of fifteen years (the “Initial Term”), with two consecutive five year renewal periods, each at the Company’s option. The aggregate rent for the Initial Term will be approximately $111.5 million. The rental rate for the renewal periods will be 95% of the Prevailing Market Rate (as defined in the Lease) and determined at the time of the exercise of the renewal. The Company is also responsible for maintaining certain insurance and the payment of proportional taxes, utilities and common area operating expenses. The Lease contains customary events of default, representations, warranties and covenants. Subject to the terms of the Lease, the Company has a right of first refusal to rent certain other space of the Campus, which would be triggered upon the Landlord’s issuance of a second round proposal or letter of intent to another tenant for such space.

Acquisitions

Acquisitions	6 Months Ended
	Jun. 30, 2020
Business Combinations [Abstract]
Acquisition	Acquisition Censa Acquisition On May 29, 2020, the Company acquired Censa, pursuant to the Censa Merger Agreement. Upon the closing of the Censa Merger, the Company paid to the Censa securityholders (i) cash consideration of $15.0 million, which consisted of an upfront payment of $10.4 million and an additional $4.6 million for the net assets on Censa's opening balance sheet as of the date of the acquisition, and (ii) 845,364 shares of the Company's common stock, which were valued at $42.9 million based on the closing stock price on the acquisition date. The number of shares issued was determined using a 30-day VWAP pursuant to the Censa Merger Agreement. The Company determined that substantially all of the fair value is concentrated in PTC923 and accounted for the transaction as an asset acquisition under ASC 805-50. The purchase price consisted of the cash consideration of $15.0 million and $42.9 million in the Company's common stock, in addition to $0.7 million of acquisition costs. As such, the total consideration transferred was determined to be $58.6 million. The opening balance sheet net assets of $4.6 million, which consisted of cash of $3.8 million and other current assets of $0.8 million, were determined to be non-qualifying assets and recorded at their fair values, respectively. The remaining consideration of $54.0 million was allocated to PTC923. As PTC923 is an IPR&D asset, the Company concluded that it did not have any alternative future use, and accordingly, the fair value amount allocated to the IPR&D was expensed. Of the $54.0 million, $53.3 million is included in research and development expense and $0.7 million is included in selling, general, and administrative expense within the Company's statement of operations for the three and six month periods ended June 30, 2020. In addition, the Company incurred $0.3 million of other expenses related to Censa, which was included in research and development expense for the three and six month periods ended June 30, 2020. Subject to the terms and conditions of the Censa Merger Agreement, Censa securityholders may become entitled to receive contingent payments from the Company based on (i) the achievement of certain development and regulatory milestones up to an aggregate maximum amount of $217.5 million for PTC923's two most advanced programs and receipt of a priority review voucher from the FDA as set forth in the Censa Merger Agreement, (ii) $109 million in development and regulatory milestones for each additional indication of PTC923, (iii) the achievement of certain net sales milestones up to an aggregate maximum amount of $160.0 million, (iv) a percentage of annual net sales during specified terms, ranging from single to low double digits of the applicable net sales threshold amount, and (v) any sublicense fees paid to the Company in consideration of any sublicense of Censa’s intellectual property to commercialize PTC923, on a country-by-country basis, which contingent payment shall equal to a mid-double digit percentage of any such sublicense fees. Pursuant to the Censa Merger Agreement, the Company has the option to pay the initial $30.0 million development milestone, for the completion of enrollment of a Phase 3 clinical trial for PTC923 for PKU, if achieved, in cash or shares of the Company’s common stock (the “Initial Milestone”). The Company will record the milestone and royalty payments when they become payable. Milestone payments prior to FDA approval of PTC923 for PKU (or other indications) will be expensed accordingly and milestone payments that will only occur after PTC923 for PKU (or other indications) is FDA approved, will be capitalized and amortized over their expected useful lives.

Fair value of financial instrum

Fair value of financial instruments and marketable securities	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Fair value of financial instruments and marketable securities	Fair value of financial instruments and marketable securities The Company follows the fair value measurement rules, which provide guidance on the use of fair value in accounting and disclosure for assets and liabilities when such accounting and disclosure is called for by other accounting literature. These rules establish a fair value hierarchy for inputs to be used to measure fair value of financial assets and liabilities. This hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels: Level 1 (highest priority), Level 2, and Level 3 (lowest priority). · Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the balance sheet date. · Level 2—Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs). · Level 3—Inputs are unobservable and reflect the Company’s assumptions as to what market participants would use in pricing the asset or liability. The Company develops these inputs based on the best information available. Cash equivalents and marketable securities are reflected in the accompanying financial statements at fair value. The carrying amount of receivables and accounts payable and accrued expenses approximates fair value due to the short-term nature of those instruments. The carrying amounts for borrowings under the credit and security agreement with MidCap Financial approximate fair value based on market activity for other debt instruments with similar characteristics and comparable risk. In May 2019, the Company purchased $4.0 million of shares of ClearPoint Neuro, Inc.'s ("ClearPoint"), formerly known as MRI Interventions, Inc., common stock, at a purchase price of $3.10 per share, in connection with a securities purchase agreement that the Company entered into with ClearPoint, a publicly traded medical device company. The Company determined that the equity investment represents a financial instrument and therefore, recorded it at fair value, which is readily determinable. The equity investment is a component of deposits and other assets on the consolidated balance sheet. During the three and six month periods ended June 30, 2020, the Company recorded unrealized losses of $0.1 million and $1.6 million, respectively, which are components of other expense, net within the consolidated statement of operations. The fair value of the equity investment was $4.6 million as of June 30, 2020. The Company classifies its equity investment in ClearPoint as a Level 1 asset within the fair value hierarchy, as the value is based on a quoted market price in an active market, which is not adjusted. In January 2020, the Company purchased a $10.0 million convertible note from ClearPoint that the Company can convert into ClearPoint shares at a conversion rate of $6.00 per share at any point throughout the term of the loan, which matures five years from the purchase date. The Company determined that the convertible note represents an available for sale debt security and the Company has elected to record it at fair value under ASC 825. The Company classifies its ClearPoint convertible debt security as a Level 2 asset within the fair value hierarchy, as the value is based on inputs other than quoted prices that are observable. The fair value of the ClearPoint convertible debt security is determined at each reporting period by utilizing a Black-Scholes option pricing model, as well as a present value of expected cash flows from the debt security utilizing the risk free rate and the estimated credit spread as of the valuation date as the discount rate. During the three and six month periods ended June 30, 2020, the Company recorded an unrealized gain of $2.1 million and an unrealized loss of $0.7 million, respectively, which are components of other expense and other income, net within the consolidated statement of operations. The fair value of the convertible debt security was $9.3 million as of June 30, 2020. The convertible debt security is considered to be long term and is included as a component of deposits and other assets on the consolidated balance sheet. Other than the equity investment and the convertible debt security, no other items included in deposits and other assets on the consolidated balance sheets are fair valued. Fair value of certain marketable securities is based upon market prices using quoted prices in active markets for identical assets quoted on the last day of the period. In establishing the estimated fair value of the remaining investments, the Company used the fair value as determined by its investment advisors using observable inputs other than quoted prices. The following represents the fair value using the hierarchy described above for the Company’s financial assets and liabilities that are required to be measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019: June 30, 2020 Total Quoted prices Significant Significant Marketable securities $ 340,430 $ — $ 340,430 $ — Equity investment in ClearPoint $ 4,594 $ 4,594 $ — $ — ClearPoint convertible debt security $ 9,251 $ — $ 9,251 $ — Deferred consideration payable $ 2,384 $ — $ 2,384 $ — Contingent consideration payable- development and regulatory milestones $ 136,100 $ — $ — $ 136,100 Contingent consideration payable- net sales milestones and royalties $ 89,600 $ — $ — $ 89,600 December 31, 2019 Total Quoted prices Significant Significant Marketable securities $ 398,535 $ — $ 398,535 $ — Equity investment in ClearPoint $ 6,194 $ 6,194 $ — $ — Stock appreciation rights liability $ 3,186 $ — $ — $ 3,186 Deferred consideration payable $ 40,000 $ — $ 40,000 $ — Contingent consideration payable- development and regulatory milestones $ 290,500 $ — $ — $ 290,500 Contingent consideration payable- net sales milestones and royalties $ 65,800 $ — $ — $ 65,800 No transfers of assets between Level 1, Level 2, or Level 3 of the fair value measurement hierarchy occurred during the periods ended June 30, 2020 and December 31, 2019. The following is a summary of marketable securities accounted for as available-for-sale securities at June 30, 2020 and December 31, 2019: June 30, 2020 Amortized Gross Unrealized Fair Gains Losses Commercial paper $ 53,638 $ 178 $ — $ 53,816 Corporate debt securities 221,068 2,882 — 223,950 Asset-backed securities 44,492 332 (1) 44,823 Government obligations 17,823 19 (1) 17,841 Total $ 337,021 $ 3,411 $ (2) $ 340,430 December 31, 2019 Amortized Gross Unrealized Fair Gains Losses Commercial paper $ 157,936 $ 162 $ — $ 158,098 Corporate debt securities 188,778 576 (20) 189,334 Asset-backed securities 51,062 49 (8) 51,103 Total $ 397,776 $ 787 $ (28) $ 398,535 For available for sale debt securities in an unrealized loss position, the Company assesses whether it intends to sell or if it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security's amortized cost basis is written down to fair value. For the three month and six month periods ended June 30, 2020, no write downs occurred. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity. The Company also reviews its available for sale debt securities in an unrealized loss position and evaluates whether the decline in fair value has resulted from credit losses or other factors. This review is subjective, as it requires management to evaluate whether an event or change in circumstances has occurred in that period that may be related to credit issues. For the three month and six month periods ended June 30, 2020, no allowance was recorded for credit losses. Unrealized gains and losses are reported as a component of accumulated other comprehensive (loss) income in stockholders’ equity. For the three month and six month periods ended June 30, 2020, the Company had $0.2 million realized gains from the sale of marketable securities. Realized gains are reported as a component of interest expense, net in the consolidated statement of operations. The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of June 30, 2020 are as follows: June 30, 2020 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized losses Fair Value Unrealized losses Fair Value Unrealized losses Fair Value Asset-backed securities (1) 594 — — (1) 594 Government obligations (1) 8,602 — — (1) 8,602 Total $ (2) $ 9,196 $ — $ — $ (2) $ 9,196 The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of December 31, 2019 are as follows: December 31, 2019 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized losses Fair Value Unrealized losses Fair Value Unrealized losses Fair Value Corporate debt securities $ (20) $ 71,779 $ — $ — $ (20) $ 71,779 Asset-backed securities (8) 24,211 — — (8) 24,211 Total $ (28) $ 95,990 $ — $ — $ (28) $ 95,990 Marketable securities on the balance sheet at June 30, 2020 and December 31, 2019 mature as follows: June 30, 2020 Less Than More Than Commercial paper $ 53,816 $ — Corporate debt securities 168,250 55,700 Asset-backed securities 26,320 18,503 Government obligations 7,201 10,640 Total Marketable securities $ 255,587 $ 84,843 December 31, 2019 Less Than More Than Commercial paper $ 158,098 $ — Corporate debt securities 139,596 49,738 Asset-backed securities 44,724 6,379 Total Marketable securities $ 342,418 $ 56,117 The Company classifies all of its marketable securities as current as they are all available for sale and are available for current operations. Convertible senior notes In August 2015, the Company issued $150.0 million of 3.00% convertible senior notes due August 15, 2022 (the “2022 Convertible Notes”). In September 2019, the Company issued $287.5 million of 1.50% convertible senior notes due September 15, 2026 (the “2026 Convertible Notes,” together with the “2022 Convertible Notes,” the “Convertible Notes”). The Company separately accounted for the liability and equity components of the Convertible Notes by allocating the proceeds between the liability component and equity component, as further discussed in Note 11. The fair value of the Convertible Notes, which differs from their carrying values, is influenced by interest rates, the Company’s stock price and stock price volatility and is determined by prices for the Convertible Notes observed in market trading which are Level 2 inputs. The estimated fair value of the 2022 Convertible Notes at June 30, 2020 and December 31, 2019 was $175.2 million and $171.2 million, respectively. The estimated fair value of the 2026 Convertible Notes at June 30, 2020 and December 31, 2019 was $343.8 million and $335.0 million, respectively. Deferred and contingent consideration payable Pursuant to the Merger Agreement, Agilis equityholders were previously entitled to receive contingent consideration payments from the Company based on the achievement of certain development milestones up to an aggregate maximum amount of $60.0 million and the achievement of certain regulatory approval milestones together with a milestone payment following the receipt of a priority review voucher up to an aggregate maximum amount of $535.0 million. The Company was required to pay $40.0 million of development milestone payments upon the passing of the second anniversary of the closing of the Merger, regardless of whether the applicable milestones have been achieved. The $40.0 million of development milestones were classified as deferred consideration on the Company's consolidated balance sheets. Pursuant to the terms of the Rights Exchange Agreement, in the three month period ended June 30, 2020, the Company issued 2,821,176 shares of its common stock and paid $36.9 million in the aggregate, to Participating Rightholders, who in exchange have canceled and forfeited their rights under the Merger Agreement to receive (i) $174.0 million, in the aggregate, of potential milestone payments based on the achievement of certain regulatory milestones and (ii) $37.6 million, in the aggregate, of $40.0 million in development milestone payments, or the deferred consideration, that would have been due upon the passing of the second anniversary of the closing of the Merger. As a result of the Rights Exchange Agreement, the remaining deferred consideration payable at June 30, 2020 was $2.4 million, which was also determined to be the fair value. The Company did not apply a discount, as the milestones will be paid within one calendar year. Accordingly, as of June 30, 2020, the $2.4 million of the deferred consideration payable was classified as current on the balance sheet. As of result of the Rights Exchange Agreement, the Company recognized a gain of $0.7 million on the settlement of the development milestones and a loss of $11.3 million on the settlement of the regulatory milestones. The $0.7 million gain and $11.3 million loss are included in the settlement of deferred and contingent consideration in the Company’s statement of operations for the three and six month periods ended June 30, 2020. Additionally, as of the date of the Rights Exchange Agreement, the Company recognized a gain on the fair value of the contingent consideration of $1.0 million related to the portion of regulatory milestones that were forfeited, which is included in the change in fair value of the deferred and contingent liability within the Company’s statement of operations for the three and six month periods ended June 30, 2020. This non-recurring Level 3 fair value measurement was estimated using the same valuation methoolody and unobservable inputs for development and regulatory milestones in the Level 3 valuation section below. In conjunction with the Rights Exchange Agreement, the Company also incurred $2.0 million of transaction fees, which were included in other expense in the Company’s statement of operations for the three and six month periods ended June 30, 2020. Level 3 valuation The stock appreciation rights ("SARs") liability is classified in other liabilities on the Company’s consolidated balance sheets. The SARs liability is marked-to-market each reporting period with the change in fair value recorded as compensation expense on the Company’s consolidated statements of operations until the SARs vest. The fair value of the SARs liability is determined at each reporting period by utilizing the Black-Scholes option pricing model. The last payment of the SARs liability was made in the three month period ended March 31, 2020, and accordingly, the balance of the SARS liability as of June 30, 2020 was $0. The contingent consideration payable is fair valued each reporting period with the change in fair value recorded as a gain or loss within the change in the fair value of deferred and contingent consideration on the consolidated statements of operations. The fair value of the development and regulatory milestones is estimated utilizing a probability adjusted, discounted cash flow approach. The discount rates are estimated utilizing Corporate B rated bonds maturing in the years of expected payments based on the Company’s estimated development timelines for the acquired product candidate. At June 30, 2020, the weighted average discount rate for the development and regulatory milestones was 5.4% and the weighted average probability of success was 43%. The fair value of the net sales milestones and royalties is determined utilizing an option pricing model with Monte Carlo simulation to simulate a range of possible payment scenarios, and the average of the payments in these scenarios is then discounted to calculate present fair value. At June 30, 2020, the weighted average discount rate for the net sales milestones and royalties was 12.0% and the weighted average probability of success for the net sales milestones was 50%. The table presented below is a summary of changes in the fair value of the Company’s Level 3 valuations for the SARs liability, and the contingent consideration payable for the periods ended June 30, 2020 and June 30, 2019. Level 3 liabilities SARs Contingent consideration payable- development and regulatory milestones Contingent consideration payable- net sales milestones and royalties Beginning balance as of December 31, 2019 $ 3,186 $ 290,500 $ 65,800 Additions — — — Change in fair value — (15,220) 23,800 Payments (3,186) — — Rights Exchange settlement — (139,180) — Ending balance as of June 30, 2020 $ — $ 136,100 $ 89,600 Level 3 liabilities SARs Contingent consideration payable- development and regulatory milestones Contingent consideration payable- net sales milestones and royalties Beginning balance as of December 31, 2018 $ 3,814 $ 257,040 $ 53,200 Additions — — — Change in fair value 1,961 20,360 5,600 Payments (3,815) — — Ending balance as of June 30, 2019 $ 1,960 $ 277,400 $ 58,800 The following significant unobservable inputs were used in the valuation of the contingent consideration payable for the periods ended June 30, 2020 and December 31, 2019 and of the SARs liability for the period ended December 31, 2019: June 30, 2020 Fair Value Valuation Technique Unobservable Input Range Contingent consideration payable- development and regulatory milestones $136,100 Probability-adjusted discounted cash flow Potential development and regulatory milestones $0 - $381 million Probabilities of success 25% - 94% Discount rates 4.6% - 6.1% Projected years of payments 2021 - 2027 Contingent considerable payable- net sales milestones and royalties $89,600 Option-pricing model with Monte Carlo simulation Potential net sales milestones $0 - $150 million Probabilities of success 25% -94% Potential percentage of net sales for royalties 2% - 6% Discount rate 12.0% Projected years of payments 2022 - 2039 December 31, 2019 Fair Value Valuation Technique Unobservable Input Range SARs $3,186 Option-pricing model Volatility 28.93% Risk free interest rate 0.19% Strike price $6.76 - $30.86 Fair value of common stock $48.03 Expected life 0.01 years Contingent consideration payable- development and regulatory milestones $290,500 Probability-adjusted discounted cash flow Potential development and regulatory milestones $0- $555 million Probabilities of success 25% - 94% Discount rates 2.2% - 4.7% Projected years of payments 2020 - 2026 Contingent considerable payable- net sales milestones and royalties $65,800 Option-pricing model with Monte Carlo simulation Potential net sales milestones $0 - $150 million Probabilities of success 25% - 89% Potential percentage of net sales for royalties 2% - 6% Discount rate 14.5% Projected years of payments 2021 - 2038 The contingent consideration payables are classified Level 3 liabilities as their valuation requires substantial judgment and estimation of factors that are not currently observable in the market. If different assumptions were used for the various inputs to the valuation approaches, including but not limited to, assumptions involving probability adjusted sales estimates for the gene therapy platform and estimated discount rates, the estimated fair value could be significantly higher or lower than the fair value determined.	Fair value of financial instruments and marketable securities The Company follows the fair value measurement rules, which provide guidance on the use of fair value in accounting and disclosure for assets and liabilities when such accounting and disclosure is called for by other accounting literature. These rules establish a fair value hierarchy for inputs to be used to measure fair value of financial assets and liabilities. This hierarchy prioritizes the inputs to valuation techniques used to measure fair value into three levels: Level 1 (highest priority), Level 2, and Level 3 (lowest priority). · Level 1—Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the balance sheet date. · Level 2—Inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs). · Level 3—Inputs are unobservable and reflect the Company’s assumptions as to what market participants would use in pricing the asset or liability. The Company develops these inputs based on the best information available. Cash equivalents and marketable securities are reflected in the accompanying financial statements at fair value. The carrying amount of receivables and accounts payable and accrued expenses approximates fair value due to the short-term nature of those instruments. The carrying amounts for borrowings under the credit and security agreement with MidCap Financial approximate fair value based on market activity for other debt instruments with similar characteristics and comparable risk. In May 2019, the Company purchased $4.0 million of shares of ClearPoint Neuro, Inc.'s ("ClearPoint"), formerly known as MRI Interventions, Inc., common stock, at a purchase price of $3.10 per share, in connection with a securities purchase agreement that the Company entered into with ClearPoint, a publicly traded medical device company. The Company determined that the equity investment represents a financial instrument and therefore, recorded it at fair value, which is readily determinable. The equity investment is a component of deposits and other assets on the consolidated balance sheet. During the three and six month periods ended June 30, 2020, the Company recorded unrealized losses of $0.1 million and $1.6 million, respectively, which are components of other expense, net within the consolidated statement of operations. The fair value of the equity investment was $4.6 million as of June 30, 2020. The Company classifies its equity investment in ClearPoint as a Level 1 asset within the fair value hierarchy, as the value is based on a quoted market price in an active market, which is not adjusted. In January 2020, the Company purchased a $10.0 million convertible note from ClearPoint that the Company can convert into ClearPoint shares at a conversion rate of $6.00 per share at any point throughout the term of the loan, which matures five years from the purchase date. The Company determined that the convertible note represents an available for sale debt security and the Company has elected to record it at fair value under ASC 825. The Company classifies its ClearPoint convertible debt security as a Level 2 asset within the fair value hierarchy, as the value is based on inputs other than quoted prices that are observable. The fair value of the ClearPoint convertible debt security is determined at each reporting period by utilizing a Black-Scholes option pricing model, as well as a present value of expected cash flows from the debt security utilizing the risk free rate and the estimated credit spread as of the valuation date as the discount rate. During the three and six month periods ended June 30, 2020, the Company recorded an unrealized gain of $2.1 million and an unrealized loss of $0.7 million, respectively, which are components of other expense and other income, net within the consolidated statement of operations. The fair value of the convertible debt security was $9.3 million as of June 30, 2020. The convertible debt security is considered to be long term and is included as a component of deposits and other assets on the consolidated balance sheet. Other than the equity investment and the convertible debt security, no other items included in deposits and other assets on the consolidated balance sheets are fair valued. Fair value of certain marketable securities is based upon market prices using quoted prices in active markets for identical assets quoted on the last day of the period. In establishing the estimated fair value of the remaining investments, the Company used the fair value as determined by its investment advisors using observable inputs other than quoted prices. The following represents the fair value using the hierarchy described above for the Company’s financial assets and liabilities that are required to be measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019: June 30, 2020 Total Quoted prices Significant Significant Marketable securities $ 340,430 $ — $ 340,430 $ — Equity investment in ClearPoint $ 4,594 $ 4,594 $ — $ — ClearPoint convertible debt security $ 9,251 $ — $ 9,251 $ — Deferred consideration payable $ 2,384 $ — $ 2,384 $ — Contingent consideration payable- development and regulatory milestones $ 136,100 $ — $ — $ 136,100 Contingent consideration payable- net sales milestones and royalties $ 89,600 $ — $ — $ 89,600 December 31, 2019 Total Quoted prices Significant Significant Marketable securities $ 398,535 $ — $ 398,535 $ — Equity investment in ClearPoint $ 6,194 $ 6,194 $ — $ — Stock appreciation rights liability $ 3,186 $ — $ — $ 3,186 Deferred consideration payable $ 40,000 $ — $ 40,000 $ — Contingent consideration payable- development and regulatory milestones $ 290,500 $ — $ — $ 290,500 Contingent consideration payable- net sales milestones and royalties $ 65,800 $ — $ — $ 65,800 No transfers of assets between Level 1, Level 2, or Level 3 of the fair value measurement hierarchy occurred during the periods ended June 30, 2020 and December 31, 2019. The following is a summary of marketable securities accounted for as available-for-sale securities at June 30, 2020 and December 31, 2019: June 30, 2020 Amortized Gross Unrealized Fair Gains Losses Commercial paper $ 53,638 $ 178 $ — $ 53,816 Corporate debt securities 221,068 2,882 — 223,950 Asset-backed securities 44,492 332 (1) 44,823 Government obligations 17,823 19 (1) 17,841 Total $ 337,021 $ 3,411 $ (2) $ 340,430 December 31, 2019 Amortized Gross Unrealized Fair Gains Losses Commercial paper $ 157,936 $ 162 $ — $ 158,098 Corporate debt securities 188,778 576 (20) 189,334 Asset-backed securities 51,062 49 (8) 51,103 Total $ 397,776 $ 787 $ (28) $ 398,535 For available for sale debt securities in an unrealized loss position, the Company assesses whether it intends to sell or if it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security's amortized cost basis is written down to fair value. For the three month and six month periods ended June 30, 2020, no write downs occurred. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases, which may be maturity. The Company also reviews its available for sale debt securities in an unrealized loss position and evaluates whether the decline in fair value has resulted from credit losses or other factors. This review is subjective, as it requires management to evaluate whether an event or change in circumstances has occurred in that period that may be related to credit issues. For the three month and six month periods ended June 30, 2020, no allowance was recorded for credit losses. Unrealized gains and losses are reported as a component of accumulated other comprehensive (loss) income in stockholders’ equity. For the three month and six month periods ended June 30, 2020, the Company had $0.2 million realized gains from the sale of marketable securities. Realized gains are reported as a component of interest expense, net in the consolidated statement of operations. The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of June 30, 2020 are as follows: June 30, 2020 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized losses Fair Value Unrealized losses Fair Value Unrealized losses Fair Value Asset-backed securities (1) 594 — — (1) 594 Government obligations (1) 8,602 — — (1) 8,602 Total $ (2) $ 9,196 $ — $ — $ (2) $ 9,196 The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of December 31, 2019 are as follows: December 31, 2019 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized losses Fair Value Unrealized losses Fair Value Unrealized losses Fair Value Corporate debt securities $ (20) $ 71,779 $ — $ — $ (20) $ 71,779 Asset-backed securities (8) 24,211 — — (8) 24,211 Total $ (28) $ 95,990 $ — $ — $ (28) $ 95,990 Marketable securities on the balance sheet at June 30, 2020 and December 31, 2019 mature as follows: June 30, 2020 Less Than More Than Commercial paper $ 53,816 $ — Corporate debt securities 168,250 55,700 Asset-backed securities 26,320 18,503 Government obligations 7,201 10,640 Total Marketable securities $ 255,587 $ 84,843 December 31, 2019 Less Than More Than Commercial paper $ 158,098 $ — Corporate debt securities 139,596 49,738 Asset-backed securities 44,724 6,379 Total Marketable securities $ 342,418 $ 56,117 The Company classifies all of its marketable securities as current as they are all available for sale and are available for current operations. Convertible senior notes In August 2015, the Company issued $150.0 million of 3.00% convertible senior notes due August 15, 2022 (the “2022 Convertible Notes”). In September 2019, the Company issued $287.5 million of 1.50% convertible senior notes due September 15, 2026 (the “2026 Convertible Notes,” together with the “2022 Convertible Notes,” the “Convertible Notes”). The Company separately accounted for the liability and equity components of the Convertible Notes by allocating the proceeds between the liability component and equity component, as further discussed in Note 11. The fair value of the Convertible Notes, which differs from their carrying values, is influenced by interest rates, the Company’s stock price and stock price volatility and is determined by prices for the Convertible Notes observed in market trading which are Level 2 inputs. The estimated fair value of the 2022 Convertible Notes at June 30, 2020 and December 31, 2019 was $175.2 million and $171.2 million, respectively. The estimated fair value of the 2026 Convertible Notes at June 30, 2020 and December 31, 2019 was $343.8 million and $335.0 million, respectively. Deferred and contingent consideration payable Pursuant to the Merger Agreement, Agilis equityholders were previously entitled to receive contingent consideration payments from the Company based on the achievement of certain development milestones up to an aggregate maximum amount of $60.0 million and the achievement of certain regulatory approval milestones together with a milestone payment following the receipt of a priority review voucher up to an aggregate maximum amount of $535.0 million. The Company was required to pay $40.0 million of development milestone payments upon the passing of the second anniversary of the closing of the Merger, regardless of whether the applicable milestones have been achieved. The $40.0 million of development milestones were classified as deferred consideration on the Company's consolidated balance sheets. Pursuant to the terms of the Rights Exchange Agreement, in the three month period ended June 30, 2020, the Company issued 2,821,176 shares of its common stock and paid $36.9 million in the aggregate, to Participating Rightholders, who in exchange have canceled and forfeited their rights under the Merger Agreement to receive (i) $174.0 million, in the aggregate, of potential milestone payments based on the achievement of certain regulatory milestones and (ii) $37.6 million, in the aggregate, of $40.0 million in development milestone payments, or the deferred consideration, that would have been due upon the passing of the second anniversary of the closing of the Merger. As a result of the Rights Exchange Agreement, the remaining deferred consideration payable at June 30, 2020 was $2.4 million, which was also determined to be the fair value. The Company did not apply a discount, as the milestones will be paid within one calendar year. Accordingly, as of June 30, 2020, the $2.4 million of the deferred consideration payable was classified as current on the balance sheet. As of result of the Rights Exchange Agreement, the Company recognized a gain of $0.7 million on the settlement of the development milestones and a loss of $11.3 million on the settlement of the regulatory milestones. The $0.7 million gain and $11.3 million loss are included in the settlement of deferred and contingent consideration in the Company’s statement of operations for the three and six month periods ended June 30, 2020. Additionally, as of the date of the Rights Exchange Agreement, the Company recognized a gain on the fair value of the contingent consideration of $1.0 million related to the portion of regulatory milestones that were forfeited, which is included in the change in fair value of the deferred and contingent liability within the Company’s statement of operations for the three and six month periods ended June 30, 2020. This non-recurring Level 3 fair value measurement was estimated using the same valuation methoolody and unobservable inputs for development and regulatory milestones in the Level 3 valuation section below. In conjunction with the Rights Exchange Agreement, the Company also incurred $2.0 million of transaction fees, which were included in other expense in the Company’s statement of operations for the three and six month periods ended June 30, 2020. Level 3 valuation The stock appreciation rights ("SARs") liability is classified in other liabilities on the Company’s consolidated balance sheets. The SARs liability is marked-to-market each reporting period with the change in fair value recorded as compensation expense on the Company’s consolidated statements of operations until the SARs vest. The fair value of the SARs liability is determined at each reporting period by utilizing the Black-Scholes option pricing model. The last payment of the SARs liability was made in the three month period ended March 31, 2020, and accordingly, the balance of the SARS liability as of June 30, 2020 was $0. The contingent consideration payable is fair valued each reporting period with the change in fair value recorded as a gain or loss within the change in the fair value of deferred and contingent consideration on the consolidated statements of operations. The fair value of the development and regulatory milestones is estimated utilizing a probability adjusted, discounted cash flow approach. The discount rates are estimated utilizing Corporate B rated bonds maturing in the years of expected payments based on the Company’s estimated development timelines for the acquired product candidate. At June 30, 2020, the weighted average discount rate for the development and regulatory milestones was 5.4% and the weighted average probability of success was 43%. The fair value of the net sales milestones and royalties is determined utilizing an option pricing model with Monte Carlo simulation to simulate a range of possible payment scenarios, and the average of the payments in these scenarios is then discounted to calculate present fair value. At June 30, 2020, the weighted average discount rate for the net sales milestones and royalties was 12.0% and the weighted average probability of success for the net sales milestones was 50%. The table presented below is a summary of changes in the fair value of the Company’s Level 3 valuations for the SARs liability, and the contingent consideration payable for the periods ended June 30, 2020 and June 30, 2019. Level 3 liabilities SARs Contingent consideration payable- development and regulatory milestones Contingent consideration payable- net sales milestones and royalties Beginning balance as of December 31, 2019 $ 3,186 $ 290,500 $ 65,800 Additions — — — Change in fair value — (15,220) 23,800 Payments (3,186) — — Rights Exchange settlement — (139,180) — Ending balance as of June 30, 2020 $ — $ 136,100 $ 89,600 Level 3 liabilities SARs Contingent consideration payable- development and regulatory milestones Contingent consideration payable- net sales milestones and royalties Beginning balance as of December 31, 2018 $ 3,814 $ 257,040 $ 53,200 Additions — — — Change in fair value 1,961 20,360 5,600 Payments (3,815) — — Ending balance as of June 30, 2019 $ 1,960 $ 277,400 $ 58,800 The following significant unobservable inputs were used in the valuation of the contingent consideration payable for the periods ended June 30, 2020 and December 31, 2019 and of the SARs liability for the period ended December 31, 2019: June 30, 2020 Fair Value Valuation Technique Unobservable Input Range Contingent consideration payable- development and regulatory milestones $136,100 Probability-adjusted discounted cash flow Potential development and regulatory milestones $0 - $381 million Probabilities of success 25% - 94% Discount rates 4.6% - 6.1% Projected years of payments 2021 - 2027 Contingent considerable payable- net sales milestones and royalties $89,600 Option-pricing model with Monte Carlo simulation Potential net sales milestones $0 - $150 million Probabilities of success 25% -94% Potential percentage of net sales for royalties 2% - 6% Discount rate 12.0% Projected years of payments 2022 - 2039 December 31, 2019 Fair Value Valuation Technique Unobservable Input Range SARs $3,186 Option-pricing model Volatility 28.93% Risk free interest rate 0.19% Strike price $6.76 - $30.86 Fair value of common stock $48.03 Expected life 0.01 years Contingent consideration payable- development and regulatory milestones $290,500 Probability-adjusted discounted cash flow Potential development and regulatory milestones $0- $555 million Probabilities of success 25% - 94% Discount rates 2.2% - 4.7% Projected years of payments 2020 - 2026 Contingent considerable payable- net sales milestones and royalties $65,800 Option-pricing model with Monte Carlo simulation Potential net sales milestones $0 - $150 million Probabilities of success 25% - 89% Potential percentage of net sales for royalties 2% - 6% Discount rate 14.5% Projected years of payments 2021 - 2038 The contingent consideration payables are classified Level 3 liabilities as their valuation requires substantial judgment and estimation of factors that are not currently observable in the market. If different assumptions were used for the various inputs to the valuation approaches, including but not limited to, assumptions involving probability adjusted sales estimates for the gene therapy platform and estimated discount rates, the estimated fair value could be significantly higher or lower than the fair value determined.

Other comprehensive income (los

Other comprehensive income (loss) and accumulated other comprehensive items	6 Months Ended
	Jun. 30, 2020
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Other comprehensive income (loss) and accumulated other comprehensive items	Other comprehensive income (loss) and accumulated other comprehensive items Other comprehensive income (loss) includes changes in equity that are excluded from net income (loss), such as unrealized gains and losses on marketable securities. The following tables summarize other comprehensive income (loss) and the changes in accumulated other comprehensive items for the three and six months periods ended June 30, 2020: Unrealized Gains/(Losses) On Marketable Securities, net of tax Foreign Currency Translation Total Accumulated Other Comprehensive Items Balance at March 31, 2020 $ 692 $ (2,677) $ (1,985) Other comprehensive income (loss) before reclassifications 2,718 (10,749) (8,031) Amounts reclassified from other comprehensive items — — — Other comprehensive income (loss) 2,718 (10,749) (8,031) Balance at June 30, 2020 $ 3,410 $ (13,426) $ (10,016) Unrealized Foreign Total Balance at December 31, 2019 $ 755 $ (11,339) $ (10,584) Other comprehensive income (loss) before reclassifications 2,655 (2,087) 568 Amounts reclassified from other comprehensive items — — — Other comprehensive income (loss) 2,655 (2,087) 568 Balance at June 30, 2020 $ 3,410 $ (13,426) $ (10,016)

Accounts payable and accrued ex

Accounts payable and accrued expenses	6 Months Ended
	Jun. 30, 2020
Payables and Accruals [Abstract]
Accounts payable and accrued expenses	Accounts payable and accrued expenses Accounts payable and accrued expenses at June 30, 2020 and December 31, 2019 consist of the following: June 30, December 31, Employee compensation, benefits, and related accruals $ 24,861 $ 38,889 Consulting and contracted research 13,452 12,969 Professional fees 3,295 3,562 Sales allowance and other costs 45,848 41,155 Sales rebates and royalties 56,870 42,997 Accounts payable 15,465 10,324 Other 4,585 9,380 Total $ 164,376 $ 159,276

Capitalization

Capitalization	6 Months Ended
	Jun. 30, 2020
Stockholders' Equity Note [Abstract]
Capitalization	Capitalization In August 2019, the Company entered into an At the Market Offering Sales Agreement (the “Sales Agreement”) with Cantor Fitzgerald and RBC Capital Markets, LLC (together, the “Sales Agents”), pursuant to which, the Company may offer and sell shares of its common stock, having an aggregate offering price of up to $125.0 million from time to time through the Sales Agents by any method that is deemed to be an “at the market offering” as defined in Rule 415(a)(4) promulgated under the Securities Act of 1933, as amended. During the three and six month periods ending June 30, 2020, the Company issued and sold an aggregate of 106,309 and 368,514 shares of common stock pursuant to the Sales Agreement at a weighted average public offering price of $53.08 and $52.89 per share, respectively. During the three and six month periods ending June 30, 2020, the Company received net proceeds of $5.4 million and $19.0 million, respectively, after deducting underwriting discounts and commissions and other offering expenses payable by the Company. As a result of the Rights Exchange Agreement, during the three and six month periods ended June 30, 2020, the Company issued 2,821,176 shares of its common stock to Participating Rightholders. The shares had a fair value of $150.5 million upon issuance. As a result of the Censa Merger, during the three and six month periods ended June 30, 2020, the Company issued 845,364 shares of the Company's common stock to Censa security holders, which were valued at $42.9 million based on the closing stock price on the acquisition date. The number of shares issued was determined using a 30-day VWAP pursuant to the Censa Merger Agreement.

Net loss per share

Net loss per share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Net loss per share	Net loss per share Basic earnings per share is computed by dividing net loss by the weighted-average number of common shares outstanding. Diluted earnings per share is computed by dividing net loss by the weighted-average number of common shares plus the effect of any dilutive potential common shares outstanding during the period. The following tables set forth the computation of basic and diluted net loss per share: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Numerator Net loss $ (181,427) $ (41,789) $ (294,114) $ (113,902) Denominator Denominator for basic and diluted net loss per share 65,150,780 55,912,748 63,769,958 57,113,141 Net loss per share: Basic and diluted $ (2.78) * $ (0.75) * $ (4.61) * $ (1.99) * *In the three and six months ended June 30, 2020 and 2019, the Company experienced a net loss and therefore did not report any dilutive share impact. The following table shows historical dilutive common share equivalents outstanding, which are not included in the above historical calculation, as the effect of their inclusion is anti-dilutive during each period. As of June 30, 2020 2019 Stock Options 11,954,684 10,853,301 Unvested restricted stock awards and units 936,922 665,002 Total 12,891,606 11,518,303

Stock award plan

Stock award plan	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Stock award plan	Stock award plan On March 5, 2013, the Company’s Board of Directors approved the 2013 Stock Incentive Plan, which provides for the granting of stock option awards, stock appreciation rights, restricted stock, restricted stock units and other stock-based awards in the aggregate of 739,937 shares of common stock. On March 5, 2013, the Company's Board of Directors approved a grant of 735,324 shares of restricted stock and 4,613 stock options. There are no additional shares available for issuance under this plan. In 2009, the Company’s shareholders approved the 2009 Equity and Long-Term Incentive Plan, which provides for the granting of stock option awards, restricted stock awards, and other stock-based and cash-based awards, subject to certain adjustments and annual increases. In May 2013, the Company’s Board of Directors and stockholders increased by 2,500,000 the number of shares authorized under the 2009 Equity and Long Term Incentive Plan, which provides for the granting of stock option awards, restricted stock awards, and other stock-based and cash-based awards. There are no additional shares available for issuance under this plan. In May 2013, the Company’s Board of Directors and stockholders approved the 2013 Long Term Incentive Plan, which became effective upon the closing of the Company’s initial public offering. The 2013 Long Term Incentive Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards and other stock-based awards. The number of shares of common stock reserved for issuance under the 2013 Long Term Incentive Plan is the sum of (1) 122,296 shares of common stock available for issuance under the Company’s 2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan, (2) the number of shares (up to 3,040,444 shares) equal to the sum of the number of shares of common stock subject to outstanding awards under the Company’s 1998 Employee, Director and Consultant Stock Option Plan, 2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right plus (3) an annual increase, to be added on the first day of each fiscal year until the expiration of the 2013 Long Term Incentive Plan, equal to the lowest of 2,500,000 shares of common stock, 4% of the number of shares of common stock outstanding on the first day of the fiscal year and an amount determined by the Company’s Board of Directors. As of June 30, 2020, awards for 914,406 shares of common stock are available for issuance under the 2013 Long Term Incentive Plan. In January 2020, the Company's Board of Directors approved the 2020 Inducement Stock Incentive Plan. The 2020 Inducement Stock Incentive Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards and other stock-based awards for up to an aggregate of 1,000,000 shares of common stock. Any grants made under the 2020 Inducement Stock Incentive Plan must be made pursuant to the Nasdaq Listing Rule 5635(c)(4) inducement grant exception as a material component of the Company's new hires’ employment compensation. As of June 30, 2020, awards for 442,880 shares of common stock are available for issuance under the 2020 Inducement Stock Incentive Plan. From January 1, 2020 through June 30, 2020, the Company issued a total of 2,515,200 stock options to various employees. Of those, 542,450 were inducement grants for non-statutory stock options, all of which were made pursuant to the 2020 Inducement Stock Incentive Plan. A summary of stock option activity is as follows: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2019 11,043,939 $ 31.67 Granted 2,515,200 $ 50.98 Exercised (1,034,288) $ 24.21 Forfeited/Cancelled (570,167) $ 42.27 Outstanding at June 30, 2020 11,954,684 $ 35.84 7.48 years $ 183,488 Vested or Expected to vest at June 30, 2020 5,690,848 $ 39.16 8.86 years $ 66,986 Exercisable at June 30, 2020 5,512,252 $ 31.61 5.85 years $ 110,222 The fair value of grants made in the six months ended June 30, 2020 was contemporaneously estimated on the date of grant using the following assumptions: Six months ended Risk-free interest rate 0.40% - 1.45% Expected volatility 87.50% - 89.31% Expected term 5.75 years The Company assumed no expected dividends for all grants. The weighted average grant date fair value of options granted during the six month period ended June 30, 2020 was $36.95 per share. The expected term of options was estimated based on the Company's historical exercise data and the expected volatility of options was estimated based on the Company's historical stock volatility. The risk-free rate of the options was based on U.S. Government Securities Treasury Constant Maturities yields at the date of grant for a term similar to the expected term of the option. Restricted Stock Awards and Restricted Stock Units —Restricted stock awards and restricted stock units are granted subject to certain restrictions, including in some cases service or time conditions (restricted stock). The grant-date fair value of restricted stock awards and restricted stock units, which have been determined based upon the market value of the Company’s shares on the grant date, are expensed over the vesting period. The following table summarizes information on the Company’s restricted stock awards and units: Restricted Stock Awards and Units Number of Weighted January 1, 2020 642,419 $ 24.50 Granted 589,070 $ 49.67 Vested (229,076) $ 23.53 Forfeited (65,491) $ 36.11 Unvested at June 30, 2020 936,922 $ 39.97 Stock Appreciation Rights —SARs entitle the holder to receive, upon exercise, an amount of the Company's common stock or cash (or a combination thereof) determined by reference to appreciation, from and after the date of grant, in the fair market value of a share of the Company's common stock over the measurement price based on the exercise date. In May 2016, a total of 897,290 SARs were granted to non-executive employees (the "2016 SARs"). The 2016 SARs vested annually in equal installments over four years and were settled in cash on each vest date, which required the Company to remeasure the SARs at each reporting period until vesting occurs. For the six month period ended June 30, 2020, a total of 132,136 SARs vested. The last payment of the SARs liability was made in the three month period ended March 31, 2020, and accordingly, the balance of the SARS liability as of June 30, 2020 was $0. Employee Stock Purchase Plan —In June 2016, the Company established an Employee Stock Purchase Plan (“ESPP” or the "Plan”) for certain eligible employees. The Plan is administered by the Company’s Board of Directors or a committee appointed by the Company's Board of Directors. The total number of shares available for purchase under the Plan is one million shares of the Company’s common stock. Employees may participate over a six month period through payroll withholdings and may purchase, at the end of the six month period, the Company’s common stock at a purchase price of at least 85% of the closing price of a share of the Company’s common stock on the first business day of the offering period or the closing price of a share of the Company’s common stock on the last business day of the offering period, whichever is lower. No participant will be granted a right to purchase the Company’s common stock under the Plan if such participant would own more than 5% of the total combined voting power of the Company or any subsidiary of the Company after such purchase. For the three and six month periods ended June 30, 2020, the Company recorded $0.3 million and $0.7 million in compensation expense related to the ESPP. The Company recorded share-based compensation expense in the statement of operations related to incentive stock options, nonstatutory stock options, restricted stock awards, restricted stock units and the ESPP as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Research and development $ 8,562 $ 5,516 $ 16,741 $ 10,203 Selling, general and administrative 8,348 5,404 15,389 9,981 Total $ 16,910 $ 10,920 $ 32,130 $ 20,184 As of June 30, 2020, there was approximately $187.2 million of total unrecognized compensation cost related to unvested share-based compensation arrangements granted under the 2009 Equity and Long Term Incentive Plan, the 2013 Long Term Incentive Plan and equity awards made pursuant to the Nasdaq Listing Rule 5635(c)(4) inducement grant exception for new hires. This cost is expected to be recognized as share-based compensation expense over the weighted average remaining service period of approximately 3.08 years.

Debt

Debt	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Debt	Debt 2017 Credit Facility In May 2017, the Company entered into the Credit Agreement, which provided for a senior secured term loan facility of $60.0 million, of which $40.0 million was drawn by the Company on May 5, 2017 (the "Credit Facility"). The Company's ability to draw on the remaining $20.0 million under the senior secured term loan facility expired on December 31, 2018. The Company capitalized approximately $0.4 million of debt issuance costs, which were netted against the carrying value of the Credit Facility and were amortized over the term of the Credit Facility. As of June 30, 2020, the Company had made loan repayments of $21.7 million on the Credit Facility. The remaining balance of the Credit Facility as of June 30, 2020 was $18.3 million, which was classified as current portion of long term debt on the consolidated balance sheet. Borrowings under the Credit Agreement bore interest at a rate per annum equal to the London Interbank Offered Rate, or LIBOR, (with a LIBOR floor rate of 1.00%) plus 6.15%. The Company was obligated to make interest only payments (payable monthly in arrears) through April 30, 2019. Commencing on May 1, 2019 and continuing for the remaining twenty-four twenty-four The Credit Facility is subject to certain financial covenants. As of June 30, 2020, the Company was in compliance with all required covenants. On July 1, 2020, the Company terminated the Credit Facility. Refer to Note 15 for further details. 2026 Convertible Notes In September 2019, the Company issued, at par value, $287.5 million aggregate principal amount of 1.50% convertible senior notes due 2026, which included an option to purchase up to an additional $37.5 million in aggregate principal amount of the 2026 Convertible Notes. The 2026 Convertible Notes bear cash interest at a rate of 1.50% per year, payable semi-annually on March 15 and September 15 of each year, beginning on March 15, 2020. The 2026 Convertible Notes will mature on September 15, 2026, unless earlier repurchased or converted. The net proceeds to the Company from the offering were $279.3 million after deducting the initial purchasers’ discounts and commissions and the offering expenses payable by the Company. The 2026 Convertible Notes are governed by an indenture (the "2026 Convertible Notes Indenture") with U.S Bank National Association as trustee (the "2026 Convertible Notes Trustee"). Holders may convert their 2026 Convertible Notes at their option at any time prior to the close of business on the business day immediately preceding March 15, 2026 only under the following circumstances: · during any calendar quarter commencing on or after December 31, 2019 (and only during such calendar quarter), if the last reported sale price of the Company’s 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 on each applicable trading day; · during the five five · during any period after the Company has issued notice of redemption until the close of business on the scheduled trading day immediately preceding the relevant redemption date; or · upon the occurrence of specified corporate events. On or after March 15, 2026, until the close of business on the business day immediately preceding the maturity date, holders may convert their 2026 Convertible Notes at any time, regardless of the foregoing circumstances. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company's common stock or any combination thereof at the Company's election. The conversion rate for the 2026 Convertible Notes was initially, and remains, 19.0404 shares of the Company’s common stock per $1,000 principal amount of the 2026 Convertible Notes, which is equivalent to an initial conversion price of approximately $52.52 per share of the Company’s common stock. The conversion rate may be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. The Company is not permitted to redeem the 2026 Convertible Notes prior to September 20, 2023. The Company may redeem for cash all or any portion of the 2026 Convertible Notes, at its option, if the last reported sale price of its common stock has been at least 130% of the conversion price then in effect on the last trading day of, and for at least 19 other trading days (whether or not consecutive) during, any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption, at a redemption price equal to 100% of the principal amount of the 2026 Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the 2026 Convertible Notes, which means that the Company is not required to redeem or retire the 2026 Convertible Notes periodically. If the Company undergoes a “fundamental change” (as defined in the 2026 Convertible Notes Indenture), subject to certain conditions, holders of the 2026 Convertible Notes may require the Company to repurchase for cash all or part of their 2026 Convertible Notes at a repurchase price equal to 100% of the principal amount of the 2026 Convertible Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. The 2026 Convertible Notes represent senior unsecured obligations and will rank senior in right of payment to the Company’s future indebtedness that is expressly subordinated in right of payment to the notes, equal in right of payment to the Company’s existing and future unsecured indebtedness that is not so subordinated, effectively junior in right of payment to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness, and structurally subordinated to all existing and future indebtedness and other liabilities (including trade payables) incurred by the Company’s subsidiaries. The 2026 Convertible Notes Indenture contains customary events of default with respect to the 2026 Convertible Notes, including that upon certain events of default (including the Company’s failure to make any payment of principal or interest on the 2026 Convertible Notes when due and payable) occurring and continuing, the 2026 Convertible Notes Trustee by notice to the Company, or the holders of at least 25% in principal amount of the outstanding 2026 Convertible Notes by notice to the Company and the Convertible Notes Trustee, may, and the 2026 Convertible Notes Trustee at the request of such holders (subject to the provisions of the 2026 Convertible Notes Indenture) shall, declare 100% of the principal of and accrued and unpaid interest, if any, on all the 2026 Convertible Notes to be due and payable. In case of certain events of bankruptcy, insolvency or reorganization, involving the Company or a significant subsidiary, 100% of the principal of and accrued and unpaid interest on the 2026 Convertible Notes will automatically become due and payable. Upon such a declaration of acceleration, such principal and accrued and unpaid interest, if any, will be due and payable immediately. The Company accounts for the 2026 Convertible Notes as a liability and equity component where the carrying value of the liability component will be valued based on a similar instrument. In accounting for the issuance of the 2026 Convertible Notes, the Company separated the 2026 Convertible Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the 2026 Convertible Notes as a whole. The excess of the principal amount of the liability component over its carrying amount, referred to as the debt discount, is amortized to interest expense over the seven In accounting for the transaction costs related to the issuance of the 2026 Convertible Notes, the Company allocated the total costs incurred to the liability and equity components of the 2026 Convertible Notes based on their relative values. Transaction costs attributable to the liability component are amortized to interest expense over the seven The 2026 Convertible Notes consist of the following: Liability component June 30, 2020 December 31, 2019 Principal $ 287,500 $ 287,500 Less: Debt issuance costs (4,319) (4,567) Less: Debt discount, net(1) (112,877) (119,350) Net carrying amount $ 170,304 $ 163,583 (1) Included in the consolidated balance sheets within convertible senior notes (due 2026) and amortized to interest expense over the remaining life of the 2026 Convertible Notes using the effective interest rate method. As of June 30, 2020, the remaining contractual life of the 2026 Convertible Notes is approximately 6.2 years. The following table sets forth total interest expense recognized related to the 2026 Convertible Notes: Three Months Ended June 30, Six Months Ended June 30, 2020 2020 Contractual interest expense $ 1,066 $ 2,142 Amortization of debt issuance costs 124 248 Amortization of debt discount 3,239 6,473 Total $ 4,429 $ 8,863 Effective interest rate of the liability component 10.2 % 10.2 % 2022 Convertible Notes In August 2015, the Company issued, at par value, $150.0 million aggregate principal amount of 3.00% convertible senior notes due 2022. The 2022 Convertible Notes bear cash interest at a rate of 3.00% per year, payable semi-annually on February 15 and August 15 of each year, beginning on February 15, 2016. The 2022 Convertible Notes will mature on August 15, 2022, unless earlier repurchased or converted. The net proceeds to the Company from the offering were $145.4 million after deducting the initial purchasers’ discounts and commissions and the offering expenses payable by the Company. The 2022 Convertible Notes are governed by an indenture (the "2022 Convertible Notes Indenture") with U.S Bank National Association as trustee (the "2022 Convertible Notes Trustee"). Holders may convert their 2022 Convertible Notes at their option at any time prior to the close of business on the business day immediately preceding February 15, 2022 only under the following circumstances: · during any calendar quarter commencing on or after September 30, 2015 (and only during such calendar quarter), if the last reported sale price of the Company’s 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 on each applicable trading day; · during the five five · during any period after the Company has issued notice of redemption until the close of business on the scheduled trading day immediately preceding the relevant redemption date; or · upon the occurrence of specified corporate events. On or after February 15, 2022, until the close of business on the business day immediately preceding the maturity date, holders may convert their 2022 Convertible Notes at any time, regardless of the foregoing circumstances. Upon conversion, the Company will pay cash up to the aggregate principal amount of the 2022 Convertible Notes to be converted and deliver shares of its common stock in respect of the remainder, if any, of its conversion obligation in excess of the aggregate principal amount of 2022 Convertible Notes being converted. The conversion rate for the 2022 Convertible Notes was initially, and remains, 17.7487 shares of the Company’s common stock per $1,000 principal amount of the 2022 Convertible Notes, which is equivalent to an initial conversion price of approximately $56.34 per share of the Company’s common stock. The conversion rate may be subject to adjustment in some events but will not be adjusted for any accrued and unpaid interest. The Company was not permitted to redeem the 2022 Convertible Notes prior to August 20, 2018. As of August 20, 2018, the Company may redeem for cash all or any portion of the 2022 Convertible Notes, at its option, if the last reported sale price of its common stock has been at least 130% of the conversion price then in effect on the last trading day of, and for at least 19 other trading days (whether or not consecutive) during, any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which the Company provides notice of redemption, at a redemption price equal to 100% of the principal amount of the 2022 Convertible Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the 2022 Convertible Notes, which means that the Company is not required to redeem or retire the 2022 Convertible Notes periodically. There have been no redemptions to date. If the Company undergoes a “fundamental change” (as defined in the 2022 Convertible Notes Indenture), subject to certain conditions, 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 to, but excluding, the fundamental change repurchase date. The 2022 Convertible Notes represent senior unsecured obligations and will rank senior in right of payment to the Company’s future indebtedness that is expressly subordinated in right of payment to the notes, equal in right of payment to the Company’s existing and future unsecured indebtedness that is not so subordinated, effectively junior in right of payment to any of the Company’s secured indebtedness to the extent of the value of the assets securing such indebtedness, and structurally subordinated to all existing and future indebtedness and other liabilities (including trade payables) incurred by the Company’s subsidiaries. The 2022 Convertible Notes Indenture contains customary events of default with respect to the 2022 Convertible Notes, including that upon certain events of default (including the Company’s failure to make any payment of principal or interest on the 2022 Convertible Notes when due and payable) occurring and continuing, the 2022 Convertible Notes Trustee by notice to the Company, or the holders of at least 25% in principal amount of the outstanding 2022 Convertible Notes by notice to the Company and the Convertible Notes Trustee, may, and the 2022 Convertible Notes Trustee at the request of such holders (subject to the provisions of the 2022 Convertible Notes Indenture) shall, declare 100% of the principal of and accrued and unpaid interest, if any, on all the 2022 Convertible Notes to be due and payable. In case of certain events of bankruptcy, insolvency or reorganization, involving the Company or a significant subsidiary, 100% of the principal of and accrued and unpaid interest on the 2022 Convertible Notes will automatically become due and payable. Upon such a declaration of acceleration, such principal and accrued and unpaid interest, if any, will be due and payable immediately. The Company accounts for the 2022 Convertible Notes as a liability and equity component where the carrying value of the liability component will be valued based on a similar instrument. In accounting for the issuance of the 2022 Convertible Notes, the Company separated the 2022 Convertible Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was determined by deducting the fair value of the liability component from the par value of the 2022 Convertible Notes as a whole. The excess of the principal amount of the liability component over its carrying amount, referred to as the debt discount, is amortized to interest expense over the seven In accounting for the transaction costs related to the issuance of the 2022 Convertible Notes, the Company allocated the total costs incurred to the liability and equity components of the 2022 Convertible Notes based on their relative values. Transaction costs attributable to the liability component are amortized to interest expense over the seven The 2022 Convertible Notes consist of the following: Liability component June 30, 2020 December 31, 2019 Principal $ 150,000 $ 150,000 Less: Debt issuance costs (1,104) (1,329) Less: Debt discount, net(1) (22,166) (26,686) Net carrying amount $ 126,730 $ 121,985 (1) Included in the consolidated balance sheets within convertible senior notes (due 2022) and amortized to interest expense over the remaining life of the 2022 Convertible Notes using the effective interest rate method. As of June 30, 2020, the remaining contractual life of the 2022 Convertible Notes is approximately 2.1 years. The following table sets forth total interest expense recognized related to the 2022 Convertible Notes: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Contractual interest expense $ 1,125 $ 1,131 $ 2,244 $ 2,241 Amortization of debt issuance costs 114 103 225 202 Amortization of debt discount 2,295 2,074 4,520 4,055 Total $ 3,534 $ 3,308 $ 6,989 $ 6,498 Effective interest rate of the liability component 11.0 % 11.0 % 11.0 % 11.0 %

Commitments and contingencies

Commitments and contingencies	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Commitments and contingencies Under various agreements, the Company will be required to pay royalties and milestone payments upon the successful development and commercialization of products. The Company has entered into funding agreements with The Wellcome Trust Limited ("Wellcome Trust") for the research and development of small molecule compounds in connection with the Company's oncology and antibacterial programs. As the Company has discontinued development under its antibacterial program, it no longer expects that milestone and royalty payments from the Company to Wellcome Trust will apply under that agreement, resulting in a change to the total amount of development and regulatory milestone payments the Company may become obligated to pay for this program. Under the oncology program funding agreement, to the extent that the Company develops and commercializes program intellectual property on a for-profit basis itself or in collaboration with a partner (provided the Company retains overall control of worldwide commercialization), the Company may become obligated to pay to Wellcome Trust development and regulatory milestone payments and single-digit royalties on sales of any research program product. The Company’s obligation to pay such royalties would continue on a country-by-country basis until the longer of the expiration of the last patent in the program intellectual property in such country covering the research program product and the expiration of market exclusivity of such product in such country. The Company’s first such milestone payment of $0.8 million payable to Wellcome Trust occurred in the second quarter of 2016. Additional milestone payments of up to an aggregate of $22.4 million may become payable by the Company to Wellcome Trust under this agreement. The Company has also entered into a collaboration agreement with the SMA Foundation. The Company may become obligated to pay the SMA Foundation single-digit royalties on worldwide net product sales of any collaboration product that is successfully developed and subsequently commercialized or, if the Company outlicenses rights to a collaboration product, a specified percentage of certain payments the Company receives from its licensee. The Company is not obligated to make such payments unless and until annual sales of a collaboration product exceed a designated threshold. The Company’s obligation to make such payments would end upon the Company's payment to the SMA Foundation of a specified amount. Pursuant to the asset purchase agreement ("Asset Purchase Agreement") between the Company and Marathon Pharmaceuticals, LLC (now known as Complete Pharma Holdings, LLC), or Marathon, Marathon is entitled to receive contingent payments from the Company based on annual net sales of Emflaza up to a specified aggregate maximum amount over the expected commercial life of the asset. In addition, Marathon has the opportunity to receive a single $50.0 million sales-based milestone. Pursuant to the Merger Agreement with Agilis, Agilis equityholders were previously entitled to receive contingent consideration payments from the Company based on (i) the achievement of certain development milestones up to an aggregate maximum amount of $60.0 million, (ii) the achievement of certain regulatory approval milestones together with a milestone payment following the receipt of a priority review voucher up to an aggregate maximum amount of $535.0 million, (iii) the achievement of certain net sales milestones up to an aggregate maximum amount of $150.0 million, and (iv) a percentage of annual net sales for Friedreich ataxia and Angelman syndrome during specified terms, ranging from 2%-6%. The Company was required to pay $40.0 million of the development milestone payments upon the passing of the second anniversary of the closing of the Merger, regardless of whether the applicable milestones have been achieved. Pursuant to the terms of the Rights Exchange Agreement, the Participating Rightholders have canceled and forfeited their rights under the Merger Agreement to receive (i) $174.0 million, in the aggregate, of potential milestone payments based on the achievement of certain regulatory milestones and (ii) $37.6 million, in the aggregate, of $40.0 million in development milestone payments that would have been due upon the passing of the second anniversary of the closing of the Merger, regardless of whether the milestones are achieved. The Rights Exchange Agreement has no effect on the Merger Agreement other than to provide for the cancellation and forfeiture of the Participating Rightholders’ rights to receive $211.6 million, in the aggregate, of the milestone payments described above. As a result, all other rights and obligations under the Merger Agreement remain in effect pursuant to their terms, including the Company’s obligation to pay up to an aggregate maximum amount of $22.4 million upon the achievement of certain development milestones (representing the remaining portion of potential development milestone payments for which rights were not canceled and forfeited pursuant to the Rights Exchange Agreement after deducting the $37.6 million for which rights were canceled and forfeited pursuant to the Rights Exchange Agreement from the $40.0 million in development milestone payments that are due upon the passing of the second anniversary of the closing of the Acquisition), up to an aggregate maximum amount of $361.0 million upon the achievement of certain regulatory milestones (representing the remaining portion of potential regulatory milestone payments for which rights were not canceled and forfeited pursuant to the Rights Exchange Agreement), up to a maximum aggregate amount of $150.0 million upon the achievement of certain net sales milestones and a percentage of annual net sales for Friedreich ataxia and Angelman syndrome during specified terms, ranging from 2% to 6%, pursuant to the terms of the Merger Agreement. Subject to the terms and conditions of the Asset Acquisition Agreement, BioElectron may become entitled to receive contingent milestone payments of up to $200.0 million (in cash or in shares of the Company’s common stock, as determined by the Company) from the Company based on the achievement of certain regulatory and net sales milestones. Subject to the terms and conditions of the Asset Acquisition Agreement, BioElectron may also become entitled to receive contingent payments based on a percentage of net sales of certain products. Subject to the terms and conditions of the Censa Merger Agreement, Censa securityholders may become entitled to receive contingent payments from the Company based on (i) the achievement of certain development and regulatory milestones up to an aggregate maximum amount of $217.5 million for PTC923's two most advanced programs and receipt of a priority review voucher from the FDA as set forth in the Censa Merger Agreement, (ii) $109 million in development and regulatory milestones for each additional indication of PTC923, (iii) the achievement of certain net sales milestones up to an aggregate maximum amount of $160.0 million, (iv) a percentage of annual net sales during specified terms, ranging from single to low double digits of the applicable net sales threshold amount, and (v) any sublicense fees paid to the Company in consideration of any sublicense of Censa’s intellectual property to commercialize PTC923, on a country-by-country basis, which contingent payment shall equal to a mid-double digit percentage of any such sublicense fees. Pursuant to the Censa Merger Agreement, the Company has the option to pay the initial $30.0 million development milestone, for the completion of enrollment of a Phase 3 clinical trial for PTC923 for PKU, if achieved, in cash or shares of the Company’s common stock. The Company also has a Collaboration and License Agreement with Akcea for the commercialization of Tegsedi and Waylivra, and products containing those compounds in countries in Latin America and the Caribbean (the "Akcea Collaboration and License Agreement"). Pursuant to the agreement, the Company paid Akcea an upfront licensing fee, which included an initial payment of $12.0 million. In 2019, a $6.0 million milestone was paid upon receipt of regulatory approval of Waylivra from the EMA and a $4.0 million milestone was paid upon regulatory approval of Tegsedi from ANVISA, the Brazilian health regulatory authority, upon receipt of regulatory approval for Waylivra from ANVISA. In addition, Akcea is eligible to receive an additional milestone payment of $4.0 million upon receipt of regulatory approval for Waylivra from ANVISA. Akcea is also entitled to receive royalty payments subject to certain terms set forth in the Akcea Collaboration and License Agreement. The Company has employment agreements with certain employees which require the funding of a specific level of payments, if certain events, such as a change in control or termination without cause, occur. Additionally, the Company has royalty payments associated with Translarna and Emflaza product net sales, payable quarterly or annually in accordance with the terms of the related agreements.

Revenue recognition

Revenue recognition	6 Months Ended
	Jun. 30, 2020
Revenue from Contract with Customer [Abstract]
Revenue recognition	Revenue recognition Net product sales The Company views its operations and manages its business in one operating segment. During the three months ended June 30, 2020 and 2019, net product sales in the United States were $36.2 million and $27.6 million, respectively, consisting solely of Emflaza, and net product sales not in the United States were $39.0 million and $57.8 million, respectively, consisting of Translarna and Tegsedi. For the three months ended June 30, 2020 and 2019, the Company had a total of two and two distributors, respectively, that each accounted for over 10% of the Company's net product sales. During the six months ended June 30, 2020 and 2019, net product sales in the United States were $63.6 million and $45.4 million, respectively, consisting solely of Emflaza, and net product sales not in the United States were $79.8 million and $93.0 million, respectively, consisting of Translarna and Tegsedi. For the six months ended June 30, 2020 and 2019, the Company had a total of two and two distributors, respectively, that each accounted for over 10% of the Company's net product sales. The Company’s contract liabilities balances as of June 30, 2020 and as of December 31, 2019 were $7.7 million and $11.7 million, respectively. The Company did not have any contract assets as of June 30, 2020 and as of December 31, 2019. During the three and six month periods ended June 30, 2020, the Company recognized $2.0 million and $4.0 million of revenue, respectively, related to the amounts included in the contract liability balance at the beginning of the period. For the three and six month periods ended June 30, 2019, the Company did not recognize any revenues relating to the contract liability balance at the beginning of the period. The Company has not made significant changes to the judgments made in applying ASC Topic 606 for the three and six month periods ending June 30, 2020 and 2019. Remaining performance obligations Remaining performance obligations represent the transaction price for goods the Company has yet to provide. As of June 30, 2020 and December 31, 2019, the aggregate amount of the transaction price allocated to the remaining performance obligations relating to Translarna net product revenue was $7.7 million and $11.7 million, respectively. The Company expects to recognize revenue within the next one year, as the specific timing for satisfying the performance obligations is contingent upon a number of factors, including customers’ needs and schedules. Collaboration revenue In November 2011, the Company and the Spinal Muscular Atrophy Foundation (SMA Foundation) entered into a licensing and collaboration agreement with F. Hoffman-La Roche Ltd and Hoffman- La Roche Inc. (collectively, Roche) for a spinal muscular atrophy program. Under the terms of the agreement, Roche acquired an exclusive worldwide license to the Company’s spinal muscular atrophy program. The Company is eligible to receive additional payments from Roche if specified events are achieved with respect to each licensed product, including up to $135.0 million in research and development event milestones, up to $325.0 million in sales milestones upon achievement of specified sales events, and up to double digit royalties on worldwide annual net sales of a commercial product. As of June 30, 2020, the remaining potential research and development event milestones that can be received is $72.5 million. The remaining potential sales milestones as of June 30, 2020 is $325.0 million upon achievement of certain sales events. In addition, the Company is eligible to receive up to double digit royalties on worldwide annual net sales of a commercial product.

Intangible assets and goodwill

Intangible assets and goodwill	6 Months Ended
	Jun. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets and goodwill	Intangible assets and goodwill Definite-lived intangibles On April 20, 2017, the Company completed its previously announced acquisition of all rights to Emflaza pursuant to the Asset Purchase Agreement, dated March 15, 2017, and amended on April 20, 2017, by and between the Company and Marathon. The assets acquired by the Company in the transaction include intellectual property rights related to Emflaza, inventories of Emflaza, and certain contractual rights related to Emflaza. In accordance with ASU 2017-01, the Company determined that substantially all of the fair value is concentrated in the Emflaza rights intangible asset and as such accounted for the transaction as an asset acquisition under ASC 805-50 and recorded an intangible asset of $148.4 million, which is being amortized to cost of product sales over its expected useful life of approximately seven years on a straight line basis. Marathon is entitled to receive contingent payments from the Company based on annual net sales of Emflaza beginning in 2018, up to a specified aggregate maximum amount over the expected commercial life of the asset. In accordance with the guidance for an asset acquisition, the Company records the milestone payment when it becomes payable to Marathon and increases the cost basis for the Emflaza rights intangible asset. As of June 30, 2020 and 2019, milestone payments of $12.2 million and $8.3 million, respectively, were recorded and are included on the balance sheet within accounts payable and accrued expenses. These payments are being amortized over the remaining useful life of the Emflaza rights asset on a straight line basis. Pursuant to the Akcea Collaboration and License Agreement, in May 2019 the Company made a $6.0 million milestone payment to Akcea upon regulatory approval of Waylivra from the EMA. The payment was recorded as an intangible asset and is being amortized to cost of product sales over its expected useful life of approximately ten years on a straight line basis. Additionally, in December 2019, the Company made a $4.0 million milestone payment to Akcea upon regulatory approval of Tegsedi from ANVISA. The payment was recorded as an intangible asset and is being amortized to cost of product sales over its expected useful life of approximately ten years on a straight line basis. Akcea is also entitled to receive royalty payments subject to certain terms set forth in the Akcea Collaboration and License Agreement related to sales of Waylivra. In accordance with the guidance for an asset acquisition, the Company will record royalty payments when they become payable to Akcea and increase the cost basis for the Waylivra intangible asset. For the three months ended June 30, 2020 and 2019, the Company recognized amortization expense of $8.7 million and $6.6 million, respectively, related to the Emflaza rights, Waylivra, and Tegsedi intangible assets. For the six months ended June 30, 2020 and 2019, the Company recognized amortization expense of $16.7 million and $12.7 million, respectively. The estimated future amortization of the Emflaza rights, Waylivra, and Tegsedi intangible assets is expected to be as follows: As of June 30, 2020 2020 $ 17,460 2021 34,920 2022 34,920 2023 34,920 2024 and thereafter 10,094 Total $ 132,314 The weighted average remaining amortization period of the definite-lived intangibles as of June 30, 2020 is 4.0 years. Indefinite-lived intangibles In connection with the acquisition of the Company’s gene therapy platform from Agilis, the Company acquired rights to PTC-AADC, for the treatment of AADC deficiency. AADC deficiency is a rare CNS disorder arising from reductions in the enzyme AADC that result from mutations in the dopa decarboxylase gene. The gene therapy platform also includes an asset targeting Friedreich ataxia, a rare and life-shortening neurodegenerative disease caused by a single defect in the FXN gene which causes reduced production of the frataxin protein. Additionally, the gene therapy platform includes two other programs targeting CNS disorders, including Angelman syndrome, a rare, genetic, neurological disorder characterized by severe developmental delays. In accordance with the acquisition method of accounting, the Company allocated the acquisition cost for the Merger to the underlying assets acquired and liabilities assumed, based upon the estimated fair values of those assets and liabilities at the date of acquisition. The Company classified the fair value of the acquired IPR&D as indefinite lived intangible assets until the successful completion or abandonment of the associated research and development efforts. The value allocated to the indefinite lived intangible assets was $576.5 million. There have been no changes to the balance of the indefinite-lived intangibles since the Merger. Goodwill As a result of the Merger on August 23, 2018, the Company recorded $82.3 million of goodwill. There were no changes to the recorded value of goodwill for the three and six month periods ended June 30, 2020.

Subsequent events

Subsequent events	6 Months Ended
	Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent events	Subsequent events MidCap Credit Facility Termination On July 1, 2020, the Company terminated the Credit Facility. In connection with the termination of the Credit Facility, the Company repaid outstanding principal and accrued interest thereunder totaling $18.4 million and paid an additional $0.6 million in termination and exit fees. All liens and security interests securing the term loan made pursuant to the Credit Facility were released upon termination.

Summary of significant accoun_2

Summary of significant accounting policies - (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The accompanying financial information as of June 30, 2020 and for the three and six months ended June 30, 2020 and 2019 has been prepared by the Company, without audit, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles in the United States ("GAAP") have been condensed or omitted pursuant to such rules and regulations. These interim financial statements should be read in conjunction with the Company’s audited financial statements as of December 31, 2019 and notes thereto included in the 2019 Form 10-K. In the opinion of management, the unaudited financial information as of June 30, 2020 and for the three and six months ended June 30, 2020 and 2019 reflects all adjustments, which are normal recurring adjustments, necessary to present a fair statement
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates in these consolidated financial statements have been made in connection with the calculation of net product sales, certain accruals related to the Company’s research and development expenses, valuation procedures for convertible notes, fair value of the contingent consideration, and the provision for or benefit from income taxes. Actual results could differ from those estimates. Changes in estimates are reflected in reported results in the period in which they become known.
Marketable securities	Marketable securitiesThe Company considers securities with original maturities of greater than 90 days to be available for sale securities. Securities under this classification are recorded at fair value and unrealized gains and losses within accumulated other comprehensive income. The estimated fair value of the available for sale securities is determined based on quoted market prices or rates for similar instruments. In addition, the cost of debt securities in this category is adjusted for amortization of premium and accretion of discount to maturity. For available for sale debt securities in an unrealized loss position, the Company assesses whether it intends to sell or if it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the security's amortized cost basis is written down to fair value. If the criteria are not met, the Company evaluates whether the decline in fair value has resulted from a credit loss or other factors. In making this assessment, management considers, among other factors, the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and adverse conditions specifically related to the security. If this assessment indicates that a credit loss exists, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of the cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses is recorded for the credit loss, limited by the amount that the fair value is less than the amortized costs basis. Any impairment that has not been recorded through an allowance for credit losses is recognized in other comprehensive income.
Inventory and cost of product sales	Inventory and cost of product sales Inventory Inventories are stated at the lower of cost and net realizable value with cost determined on a first-in, first-out basis by product. The Company capitalizes inventory costs associated with products following regulatory approval when future commercialization is considered probable and the future economic benefit is expected to be realized. Products which may be used in clinical development programs are included in inventory and charged to research and development expense when the product enters the research and development process and no longer can be used for commercial purposes. Inventory used for marketing efforts are charged to selling, general and administrative expense. Amounts related to clinical development programs and marketing efforts are immaterial. The following table summarizes the components of the Company’s inventory for the periods indicated: June 30, 2020 December 31, 2019 Raw materials $ 877 $ 874 Work in progress 8,666 9,652 Finished goods 8,830 8,759 Total inventory $ 18,373 $ 19,285 The Company periodically reviews its inventories for excess amounts or obsolescence and writes down obsolete or otherwise unmarketable inventory to its estimated net realizable value. For the three months ended June 30, 2020, inventory write downs were immaterial. For the six months ended June 30, 2020, the Company recorded a $0.2 million inventory write-down, primarily related to product approaching expiration. No write downs were recorded for the three and six month periods ended June 30, 2019. Additionally, though the Company’s product is subject to strict quality control and monitoring which it performs throughout the manufacturing processes, certain batches or units of product may not meet quality specifications resulting in a charge to cost of product sales. For the three and six month periods ended June 30, 2020 and 2019, these amounts were immaterial. Cost of product sales Cost of product sales consists of the cost of inventory sold, manufacturing and supply chain costs, storage costs, amortization of the acquired intangible asset and royalty payments associated with net product sales. Production costs are expensed as cost of product sales when the related products are sold.
Allowance for doubtful accounts	Allowance for doubtful accountsThe Company maintains an allowance for estimated losses resulting from the inability of its customers to make required payments. The Company estimates uncollectible amounts based upon current customer receivable balances, the age of customer receivable balances, the customer’s financial condition and current economic trends.
Indefinite-lived intangible assets	Indefinite-lived intangible assets Indefinite-lived intangible assets consist of in process research and development ("IPR&D"). IPR&D acquired directly in a transaction other than a business combination is capitalized if the projects will be further developed or have an alternative future use; otherwise they are expensed. The fair values of IPR&D projects and license agreement assets acquired in business combinations are capitalized. Several methods may be used to determine the estimated fair value of the IPR&D and license agreement asset acquired in a business combination. The Company utilizes the "income method” and uses estimated future net cash flows that are derived from projected sales revenues and estimated costs. These projections are based on factors such as relevant market size, patent protection, and expected pricing and industry trends. The estimated future net cash flows are then discounted to the present value using an appropriate discount rate. These assets are treated as indefinite-lived intangible assets until completion or abandonment of the projects, at which time the assets are amortized over the remaining useful life or written off, as appropriate. Intangible assets with indefinite lives, including IPR&D, are tested for impairment if impairment indicators arise and, at a minimum, annually. However, an entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that an indefinite-lived intangible asset’s fair value is less than its carrying amount. Otherwise, no further impairment testing is required. The indefinite-lived intangible asset impairment test consists of a one-step analysis that compares the fair value of the intangible asset with its carrying amount. If the carrying amount of an intangible asset exceeds its fair value, an impairment loss is recognized in an amount equal to that excess. The Company considers many factors in evaluating whether the value of its intangible assets with indefinite lives may not be recoverable, including, but not
Goodwill	Goodwill Goodwill represents the amount of consideration paid in excess of the fair value of net assets acquired as a result of the Company’s business acquisitions accounted for using the acquisition method of accounting. Goodwill is not amortized and is subject to impairment testing at a reporting unit level on an annual basis or when a triggering event occurs that may indicate the carrying value of the goodwill is impaired. The Company reassess its reporting units as part of its annual segment review. An entity is permitted to first assess qualitative factors to determine if a quantitative impairment test is necessary. Further testing is only required if the entity determines, based on the qualitative assessment, that it is more likely than not that the fair value of the reporting unit is less than its carrying amount.
Income Taxes	Income Taxes O n March 27, 2020, the United States enacted the Coronavirus Aid, Relief, and Economic Security Act, referred to herein as the CARES Act, as a response to the economic uncertainty resulting from a strain of novel coronavirus, COVID-19. The CARES Act includes modifications for net operating loss carryovers and carrybacks, limitations of business interest expense for tax, immediate refund of alternative minimum tax (AMT) credit carryovers as well as a technical correction to the 2017 Tax Cuts and Jobs Act ("the 2017 Tax Act"), referred to herein as the U.S. Tax Act, for qualified improvement property. As of June 30, 2020, the Company expects that these provisions will not have a material impact. Tax provisions of the Act also include the deferral of certain payroll taxes, relief for retaining employees, and other provisions. The Company is evaluating the impact of the Act and currently expects to benefit from the deferral of certain payroll taxes and retention credit through the end of calendar year 2020. The ultimate impact of the CARES Act may differ from this estimate due to changes in interpretations and guidance that may be issued and actions the Company may take in response to the CARES Act. The Company will continue to assess the impact that various provisions will have on its business. On December 22, 2017, the U.S. government enacted the 2017 Tax Act, which significantly revises U.S. tax law by, among other provisions, lowering the U.S. federal statutory income tax rate to 21%, imposing a mandatory one-time transition tax on previously deferred foreign earnings, and eliminating or reducing certain income tax deductions. The Global Intangible Low-tax Income ("GILTI") provisions of the 2017 Tax Act require the Company to include in its U.S. income tax return foreign subsidiary earnings in excess of an allowable return on the foreign subsidiary’s tangible assets. The Company has elected to account for GILTI tax in the period in which it is incurred, and therefore has not provided any deferred tax impacts of GILTI in its consolidated financial statements for the period ended June 30, 2020. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and net operating loss and credit carryforwards. Deferred tax assets and liabilities are measured at rates expected to apply to taxable income in the years in which those temporary differences and carryforwards are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the statement of operations in the period that includes the enactment date. A valuation allowance is recorded when it is not more likely than not that all or a portion of the net deferred tax assets will be realized. The Company recorded a deferred tax liability in conjunction with the Merger of $122.0 million related to the tax basis difference in the IPR&D indefinite-lived intangibles acquired. The Company's policy is to record a deferred tax liability related to acquired IPR&D which may eventually be realized either upon amortization of the asset when the research is completed and a product is successfully launched or the write-off of the asset if it is abandoned or unsuccessful.
Leases	Leases The Company determines if an arrangement is a lease at inception. This determination generally depends on whether the arrangement conveys to the Company the right to control the use of an explicitly or implicitly identified fixed asset for a period of time in exchange for consideration. Control of an underlying asset is conveyed to the Company if the Company obtains the rights to direct the use of and to obtain substantially all of the economic benefits from using the underlying asset. The Company has lease agreements which include lease and non-lease components, which the Company accounts for as a single lease component for all leases. Operating and finance leases are classified as right of use ("ROU") assets, short term lease liabilities, and long term lease liabilities. Operating and finance lease ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. ROU assets are amortized and lease liabilities accrete to yield straight-line expense over the term of the lease. Lease payments included in the measurement of the lease liability are comprised of fixed payments. Variable lease payments associated with the Company’s leases are recognized when the event, activity, or circumstance in the lease agreement on which those payments are assessed occurs. Variable lease payments are presented in the Company’s consolidated statements of operations in the same line item as expense arising from fixed lease payments for operating leases. Leases with an initial term of 12 months or less are not recorded on the consolidated balance sheet and the Company recognizes lease expense for these leases on a straight-line basis over the lease term. The Company applies this policy to all underlying asset categories. A lessee is required to discount its unpaid lease payments using the interest rate implicit in the lease or, if that rate cannot be readily determined, its incremental borrowing rate. As most of the Company’s leases do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The Company gives consideration to its recent debt issuances as well as publicly available data for instruments with similar characteristics when calculating its incremental borrowing rates.
Recently issued accounting standards	Impact of recently adopted accounting pronouncements In December 2019, the FASB issued ASU 2019-12,"Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes”. ASU 2019-12 simplifies the accounting for income taxes by removing certain exceptions to the general principals in Topic 740. The amendments also improve consistent application of and simplify GAAP for other areas of Topic 740 by clarifying and amending the existing guidance. For public business entities, the guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2020. For all other entities, it is effective for annual periods beginning after December 15, 2021 and interim periods in annual periods beginning after December 15, 2022. Early adoption is permitted, including adoption in any interim period. The Company early adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements and accompanying notes. In June 2016, the FASB issued ASU No. 2016-13, “Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments”. This standard requires financial assets measured at amortized cost basis to be presented at the net amount expected to be collected. This standard is effective for public companies who are SEC filers for fiscal years beginning after December 15, 2019, including interim periods within those years. In November 2019, the FASB issued ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, which expands the scope of the practical expedient that allows entities to exclude the accrued interest component of amortized cost from various disclosures required by ASC 326 to also include certain disclosures required by ASC 320. Entities that elect to apply the practical expedient must disclose the total amount of accrued interest that they exclude from their disclosures of amortized cost. The amendments have the same effective dates as ASU 2016-13 (Topic 326) for entities that have not yet adopted that standard. The Company adopted ASU 2016-13 and ASU 2019-11 effective January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements. The Company has updated its accounting policy for marketable securities within this footnote as well as its fair value footnote (Note 5) with additional disclosures as required by the standard upon adoption. In August 2018, the FASB issued ASU 2018-13, "Fair Value Measurement (Topic 820), Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement". This standard eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information and modifies some disclosure requirements. The new guidance is effective for all entities for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years. An entity is permitted to early adopt either the entire standard or only the provisions that eliminate or modify requirements. Entities can elect to early adopt in interim periods, including periods for which they have not yet issued financial statements or made their financial statements available for issuance. The Company adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements. The Company has updated its fair value footnote (Note 5) with additional and modified disclosures as required by the standard upon adoption. In August 2018, the FASB issued ASU 2018-15,"Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract". ASU 2018-15 requires a customer in a cloud computing arrangement that is a service contract to follow the internal-use software guidance in Accounting Standards Codification 350-40 to determine which implementation costs to defer and recognize as an asset. For public business entities, the guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2019. For all other entities, it is effective for annual periods beginning after December 15, 2020 and interim periods in annual periods beginning after December 15, 2021. Early adoption is permitted, including adoption in any interim period for all entities. The Company adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements and accompanying notes. In November 2018, the FASB issued ASU 2018-18,"Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606”. ASU 2018-18 provides guidance on whether certain transactions between collaborative arrangement participants should be accounted for with revenue under Topic 606. For public business entities, the guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2019. For all other entities, it is effective for annual periods beginning after December 15, 2020 and interim periods in annual periods beginning after December 15, 2021. Early adoption is permitted, including adoption in any interim period for all entities. The Company adopted this guidance January 1, 2020. The adoption of the guidance did not have a material impact on the consolidated financial statements and accompanying notes.

Summary of significant accoun_3

Summary of significant accounting policies - (Tables)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Reconciliation of cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the consolidated balance sheet that sum to the total of the same amounts shown in the statement of cash flows: Beginning of period- December 31, 2019 End of period- June 30, 2020 Cash and cash equivalents $ 288,028 $ 158,461 Restricted cash included in deposits and other assets 7,500 7,500 Total Cash, cash equivalents and restricted cash per statement of cash flows $ 295,528 $ 165,961
Schedule of Inventory	The following table summarizes the components of the Company’s inventory for the periods indicated: June 30, 2020 December 31, 2019 Raw materials $ 877 $ 874 Work in progress 8,666 9,652 Finished goods 8,830 8,759 Total inventory $ 18,373 $ 19,285

Leases - (Tables)

Leases - (Tables)	6 Months Ended
	Jun. 30, 2020
Leases [Abstract]
Lease costs	The components of operating lease expense were as follows: Three Months Ended June 30, 2020 Three Months Ended June 30, 2019 Six Months Ended June 30, 2020 Six Months Ended June 30, 2019 Operating Lease Cost Fixed lease cost $ 1,970 $ 835 $ 4,089 $ 1,647 Variable lease cost 507 161 734 304 Short-term lease cost 88 88 165 141 Total operating lease cost $ 2,565 $ 1,084 $ 4,988 $ 2,092 Total operating lease cost is a component of operating expenses on the consolidated statements of operations. Supplemental balance sheet information related to leases was as follows: June 30, 2020 December 31, 2019 Operating lease ROU asset $ 29,475 $ 13,693 Operating lease liabilities- current $ 4,868 $ 5,153 Operating lease liabilities- noncurrent 25,510 9,018 Total operating lease liability $ 30,378 $ 14,171 June 30, 2020 December 31, 2019 Finance lease liabilities- current $ 4,180 $ — Finance lease liabilities- noncurrent 22,031 — Total finance lease liability $ 26,211 $ — June 30, 2020 December 31, 2019 Weighted-average remaining lease terms - operating leases (years) 5.87 3.38 Weighted-average discount rate - operating leases 6.77 % 7.33 % Weighted-average remaining lease terms - finance lease (years) 12.50 — Weighted-average discount rate - finance lease 7.80 % — Supplemental cash flow information related to leases was as follows as of June 30, 2020 and 2019: Six Month Ended June 30, 2020 2019 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 3,414 $ 1,508 Financing cash flows from finance lease 15,000 — Right-of-use assets obtained in exchange for lease obligations: Operating leases $ 18,117 $ 11,643 Finance lease 41,212 —
Lease payments	Future minimum lease payments under non-cancelable leases as of June 30, 2020 were as follows: Operating Leases Finance Lease 2020 (excludes the six months ended June 30, 2020) $ 3,719 $ 3,000 2021 6,667 3,000 2022 6,314 3,000 2023 5,960 3,000 2024 and thereafter 14,844 27,000 Total lease payments 37,504 39,000 Less: Imputed Interest expense 7,126 12,789 Total $ 30,378 $ 26,211

Fair value of financial instr_2

Fair value of financial instruments and marketable securities - (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of financial assets and liabilities that are required to be measured at fair value on a recurring basis	The following represents the fair value using the hierarchy described above for the Company’s financial assets and liabilities that are required to be measured at fair value on a recurring basis as of June 30, 2020 and December 31, 2019: June 30, 2020 Total Quoted prices Significant Significant Marketable securities $ 340,430 $ — $ 340,430 $ — Equity investment in ClearPoint $ 4,594 $ 4,594 $ — $ — ClearPoint convertible debt security $ 9,251 $ — $ 9,251 $ — Deferred consideration payable $ 2,384 $ — $ 2,384 $ — Contingent consideration payable- development and regulatory milestones $ 136,100 $ — $ — $ 136,100 Contingent consideration payable- net sales milestones and royalties $ 89,600 $ — $ — $ 89,600 December 31, 2019 Total Quoted prices Significant Significant Marketable securities $ 398,535 $ — $ 398,535 $ — Equity investment in ClearPoint $ 6,194 $ 6,194 $ — $ — Stock appreciation rights liability $ 3,186 $ — $ — $ 3,186 Deferred consideration payable $ 40,000 $ — $ 40,000 $ — Contingent consideration payable- development and regulatory milestones $ 290,500 $ — $ — $ 290,500 Contingent consideration payable- net sales milestones and royalties $ 65,800 $ — $ — $ 65,800
Summary of marketable securities accounted for as available-for-sale securities	The following is a summary of marketable securities accounted for as available-for-sale securities at June 30, 2020 and December 31, 2019: June 30, 2020 Amortized Gross Unrealized Fair Gains Losses Commercial paper $ 53,638 $ 178 $ — $ 53,816 Corporate debt securities 221,068 2,882 — 223,950 Asset-backed securities 44,492 332 (1) 44,823 Government obligations 17,823 19 (1) 17,841 Total $ 337,021 $ 3,411 $ (2) $ 340,430 December 31, 2019 Amortized Gross Unrealized Fair Gains Losses Commercial paper $ 157,936 $ 162 $ — $ 158,098 Corporate debt securities 188,778 576 (20) 189,334 Asset-backed securities 51,062 49 (8) 51,103 Total $ 397,776 $ 787 $ (28) $ 398,535
Summary of unrealized losses and fair values of available-for-sale securities in a continuous unrealized loss position	The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of June 30, 2020 are as follows: June 30, 2020 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized losses Fair Value Unrealized losses Fair Value Unrealized losses Fair Value Asset-backed securities (1) 594 — — (1) 594 Government obligations (1) 8,602 — — (1) 8,602 Total $ (2) $ 9,196 $ — $ — $ (2) $ 9,196 The unrealized losses and fair values of available-for-sale securities that have been in an unrealized loss position for a period of less than and greater than 12 months as of December 31, 2019 are as follows: December 31, 2019 Securities in an unrealized loss position less than 12 months Securities in an unrealized loss position greater than 12 months Total Unrealized losses Fair Value Unrealized losses Fair Value Unrealized losses Fair Value Corporate debt securities $ (20) $ 71,779 $ — $ — $ (20) $ 71,779 Asset-backed securities (8) 24,211 — — (8) 24,211 Total $ (28) $ 95,990 $ — $ — $ (28) $ 95,990
Schedule of marketable securities on the balance sheet	Marketable securities on the balance sheet at June 30, 2020 and December 31, 2019 mature as follows: June 30, 2020 Less Than More Than Commercial paper $ 53,816 $ — Corporate debt securities 168,250 55,700 Asset-backed securities 26,320 18,503 Government obligations 7,201 10,640 Total Marketable securities $ 255,587 $ 84,843 December 31, 2019 Less Than More Than Commercial paper $ 158,098 $ — Corporate debt securities 139,596 49,738 Asset-backed securities 44,724 6,379 Total Marketable securities $ 342,418 $ 56,117
Summary of changes in the fair value of the Company's Level 3 valuation for warrant liability and SARs liability	The following significant unobservable inputs were used in the valuation of the contingent consideration payable for the periods ended June 30, 2020 and December 31, 2019 and of the SARs liability for the period ended December 31, 2019: June 30, 2020 Fair Value Valuation Technique Unobservable Input Range Contingent consideration payable- development and regulatory milestones $136,100 Probability-adjusted discounted cash flow Potential development and regulatory milestones $0 - $381 million Probabilities of success 25% - 94% Discount rates 4.6% - 6.1% Projected years of payments 2021 - 2027 Contingent considerable payable- net sales milestones and royalties $89,600 Option-pricing model with Monte Carlo simulation Potential net sales milestones $0 - $150 million Probabilities of success 25% -94% Potential percentage of net sales for royalties 2% - 6% Discount rate 12.0% Projected years of payments 2022 - 2039 December 31, 2019 Fair Value Valuation Technique Unobservable Input Range SARs $3,186 Option-pricing model Volatility 28.93% Risk free interest rate 0.19% Strike price $6.76 - $30.86 Fair value of common stock $48.03 Expected life 0.01 years Contingent consideration payable- development and regulatory milestones $290,500 Probability-adjusted discounted cash flow Potential development and regulatory milestones $0- $555 million Probabilities of success 25% - 94% Discount rates 2.2% - 4.7% Projected years of payments 2020 - 2026 Contingent considerable payable- net sales milestones and royalties $65,800 Option-pricing model with Monte Carlo simulation Potential net sales milestones $0 - $150 million Probabilities of success 25% - 89% Potential percentage of net sales for royalties 2% - 6% Discount rate 14.5% Projected years of payments 2021 - 2038
Fair Value Measurement Inputs and Valuation Techniques	The table presented below is a summary of changes in the fair value of the Company’s Level 3 valuations for the SARs liability, and the contingent consideration payable for the periods ended June 30, 2020 and June 30, 2019. Level 3 liabilities SARs Contingent consideration payable- development and regulatory milestones Contingent consideration payable- net sales milestones and royalties Beginning balance as of December 31, 2019 $ 3,186 $ 290,500 $ 65,800 Additions — — — Change in fair value — (15,220) 23,800 Payments (3,186) — — Rights Exchange settlement — (139,180) — Ending balance as of June 30, 2020 $ — $ 136,100 $ 89,600 Level 3 liabilities SARs Contingent consideration payable- development and regulatory milestones Contingent consideration payable- net sales milestones and royalties Beginning balance as of December 31, 2018 $ 3,814 $ 257,040 $ 53,200 Additions — — — Change in fair value 1,961 20,360 5,600 Payments (3,815) — — Ending balance as of June 30, 2019 $ 1,960 $ 277,400 $ 58,800

Other comprehensive income (l_2

Other comprehensive income (loss) and accumulated other comprehensive items - (Tables)	6 Months Ended
	Jun. 30, 2020
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Summary of other comprehensive income (loss) and the changes in accumulated other comprehensive items	The following tables summarize other comprehensive income (loss) and the changes in accumulated other comprehensive items for the three and six months periods ended June 30, 2020: Unrealized Gains/(Losses) On Marketable Securities, net of tax Foreign Currency Translation Total Accumulated Other Comprehensive Items Balance at March 31, 2020 $ 692 $ (2,677) $ (1,985) Other comprehensive income (loss) before reclassifications 2,718 (10,749) (8,031) Amounts reclassified from other comprehensive items — — — Other comprehensive income (loss) 2,718 (10,749) (8,031) Balance at June 30, 2020 $ 3,410 $ (13,426) $ (10,016) Unrealized Foreign Total Balance at December 31, 2019 $ 755 $ (11,339) $ (10,584) Other comprehensive income (loss) before reclassifications 2,655 (2,087) 568 Amounts reclassified from other comprehensive items — — — Other comprehensive income (loss) 2,655 (2,087) 568 Balance at June 30, 2020 $ 3,410 $ (13,426) $ (10,016)

Accounts payable and accrued _2

Accounts payable and accrued expenses - (Tables)	6 Months Ended
	Jun. 30, 2020
Payables and Accruals [Abstract]
Schedule of components of accounts payable and accrued expenses	Accounts payable and accrued expenses at June 30, 2020 and December 31, 2019 consist of the following: June 30, December 31, Employee compensation, benefits, and related accruals $ 24,861 $ 38,889 Consulting and contracted research 13,452 12,969 Professional fees 3,295 3,562 Sales allowance and other costs 45,848 41,155 Sales rebates and royalties 56,870 42,997 Accounts payable 15,465 10,324 Other 4,585 9,380 Total $ 164,376 $ 159,276

Net loss per share - (Tables)

Net loss per share - (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted net loss available to common stockholders	The following tables set forth the computation of basic and diluted net loss per share: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Numerator Net loss $ (181,427) $ (41,789) $ (294,114) $ (113,902) Denominator Denominator for basic and diluted net loss per share 65,150,780 55,912,748 63,769,958 57,113,141 Net loss per share: Basic and diluted $ (2.78) * $ (0.75) * $ (4.61) * $ (1.99) * *In the three and six months ended June 30, 2020 and 2019, the Company experienced a net loss and therefore did not report any dilutive share impact.
Schedule of historical dilutive common share equivalents outstanding	The following table shows historical dilutive common share equivalents outstanding, which are not included in the above historical calculation, as the effect of their inclusion is anti-dilutive during each period. As of June 30, 2020 2019 Stock Options 11,954,684 10,853,301 Unvested restricted stock awards and units 936,922 665,002 Total 12,891,606 11,518,303

Stock award plan - (Tables)

Stock award plan - (Tables)	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Summary of stock option activity	A summary of stock option activity is as follows: Number of Weighted- Weighted- Aggregate Outstanding at December 31, 2019 11,043,939 $ 31.67 Granted 2,515,200 $ 50.98 Exercised (1,034,288) $ 24.21 Forfeited/Cancelled (570,167) $ 42.27 Outstanding at June 30, 2020 11,954,684 $ 35.84 7.48 years $ 183,488 Vested or Expected to vest at June 30, 2020 5,690,848 $ 39.16 8.86 years $ 66,986 Exercisable at June 30, 2020 5,512,252 $ 31.61 5.85 years $ 110,222
Schedule of assumptions used to estimate fair values of grants made on the date of grant	The fair value of grants made in the six months ended June 30, 2020 was contemporaneously estimated on the date of grant using the following assumptions: Six months ended Risk-free interest rate 0.40% - 1.45% Expected volatility 87.50% - 89.31% Expected term 5.75 years
Summary of information on the Company's restricted stock	The following table summarizes information on the Company’s restricted stock awards and units: Restricted Stock Awards and Units Number of Weighted January 1, 2020 642,419 $ 24.50 Granted 589,070 $ 49.67 Vested (229,076) $ 23.53 Forfeited (65,491) $ 36.11 Unvested at June 30, 2020 936,922 $ 39.97
Schedule of share-based compensation expense recorded in the statement of operations	The Company recorded share-based compensation expense in the statement of operations related to incentive stock options, nonstatutory stock options, restricted stock awards, restricted stock units and the ESPP as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Research and development $ 8,562 $ 5,516 $ 16,741 $ 10,203 Selling, general and administrative 8,348 5,404 15,389 9,981 Total $ 16,910 $ 10,920 $ 32,130 $ 20,184

Debt - (Tables)

Debt - (Tables)	6 Months Ended
	Jun. 30, 2020
1.50% Convertible senior notes due 2026
Debt Instrument, Redemption [Line Items]
Summary of convertible notes	The 2026 Convertible Notes consist of the following: Liability component June 30, 2020 December 31, 2019 Principal $ 287,500 $ 287,500 Less: Debt issuance costs (4,319) (4,567) Less: Debt discount, net(1) (112,877) (119,350) Net carrying amount $ 170,304 $ 163,583 (1) Included in the consolidated balance sheets within convertible senior notes (due 2026) and amortized to interest expense over the remaining life of the 2026 Convertible Notes using the effective interest rate method.
Summary of interest expense recognized related to the Convertible Notes	The following table sets forth total interest expense recognized related to the 2026 Convertible Notes: Three Months Ended June 30, Six Months Ended June 30, 2020 2020 Contractual interest expense $ 1,066 $ 2,142 Amortization of debt issuance costs 124 248 Amortization of debt discount 3,239 6,473 Total $ 4,429 $ 8,863 Effective interest rate of the liability component 10.2 % 10.2 %
3.00% Convertible senior notes due 2022
Debt Instrument, Redemption [Line Items]
Summary of convertible notes	The 2022 Convertible Notes consist of the following: Liability component June 30, 2020 December 31, 2019 Principal $ 150,000 $ 150,000 Less: Debt issuance costs (1,104) (1,329) Less: Debt discount, net(1) (22,166) (26,686) Net carrying amount $ 126,730 $ 121,985 (1) Included in the consolidated balance sheets within convertible senior notes (due 2022) and amortized to interest expense over the remaining life of the 2022 Convertible Notes using the effective interest rate method.
Summary of interest expense recognized related to the Convertible Notes	The following table sets forth total interest expense recognized related to the 2022 Convertible Notes: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Contractual interest expense $ 1,125 $ 1,131 $ 2,244 $ 2,241 Amortization of debt issuance costs 114 103 225 202 Amortization of debt discount 2,295 2,074 4,520 4,055 Total $ 3,534 $ 3,308 $ 6,989 $ 6,498 Effective interest rate of the liability component 11.0 % 11.0 % 11.0 % 11.0 %

Intangible assets and goodwill

Intangible assets and goodwill - (Tables)	6 Months Ended
	Jun. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Future amortization expense	As of June 30, 2020 2020 $ 17,460 2021 34,920 2022 34,920 2023 34,920 2024 and thereafter 10,094 Total $ 132,314

The Company - Narrative (Detail

The Company - Narrative (Details) - USD ($) $ in Thousands	Apr. 29, 2020	Aug. 23, 2018	Jun. 30, 2020	Jun. 29, 2020	Dec. 31, 2019	Apr. 20, 2017	Aug. 31, 2015
Long-term debt
Retained earnings (accumulated deficit)			$ (1,484,831)		$ (1,190,499)
Rights Exchange Agreement [Member]
Long-term debt
Shares to issue under Rights Exchange Agreement	2,821,176
Cash consideration payment under Rights Exchange Agreement	$ 36,900
Convertible debt | 1.50% Convertible senior notes due 2026
Long-term debt
Interest rate ( as a percent )			1.50%		1.50%
Convertible debt | 3.00% Convertible senior notes due 2022
Long-term debt
Interest rate ( as a percent )							3.00%
Non-collaborative Arrangement Transactions | Marathon Pharmaceuticals, LLC
Long-term debt
Development milestone payments which the entity is obligated to pay						$ 50,000
Agilis
Long-term debt
Cash consideration		$ 49,200
Equity Interest Issued, number of shares (in shares)		3,500,907
Numerator for calculation of number of shares of equity interests issued to acquire entity		$ 150,000
Trading day period		10 days
Development milestone payments which the entity is obligated to pay	40,000		$ 40,000
Development Milestone Payment Obligations, Net of Cancellation and Forfeiture			$ 22,400
Net sales amount	$ 150,000
Agilis | Minimum
Long-term debt
Development milestone payments which the entity is obligated to pay				$ 37,600
Product sales	2.00%		2.00%
Agilis | Maximum
Long-term debt
Development milestone payments which the entity is obligated to pay			$ 60,000	$ 40,000
Priority review voucher amount			535,000
Net sales amount			$ 150,000
Product sales	6.00%		6.00%
Agilis | Rights Exchange Agreement [Member]
Long-term debt
Priority review voucher amount	$ 174,000
Development Milestone Payment Obligations, Net of Cancellation and Forfeiture	22,400
Contingent Liability, Milestone, Potential Achievements, Priority Review Voucher Amount, Net of Cancellation and Forfeiture	$ 361,000
Agilis | Rights Exchange Agreement [Member] | Maximum
Long-term debt
Contingent Liability, Milestone, Potential Achievements, Priority Review Voucher Amount, Net of Cancellation and Forfeiture			$ 361,000
Agilis | Non-collaborative Arrangement Transactions
Long-term debt
Development milestone payments which the entity is obligated to pay			$ 40,000

Summary of significant accoun_4

Summary of significant accounting policies - Inventory (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Raw materials	$ 877	$ 874
Work in progress	8,666	9,652
Finished goods	8,830	8,759
Total inventory	$ 18,373	$ 19,285

Summary of significant accoun_5

Summary of significant accounting policies - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Allowance for credit loss	$ 0		$ 0
Inventory write-down		$ 0	200,000	$ 0
Letters of Credit	7,500,000		$ 7,500,000
Term for letter of credit (in years)			5 years
Operating lease ROU asset	29,475,000		$ 29,475,000		$ 13,693,000
Allowance for doubtful accounts receivable	200,000		200,000		300,000
Deferred tax liability					$ 122,000,000
Accounts receivable, allowance for credit loss,	0		0
Fifth Anniversary
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Letters of Credit	$ 3,800,000		$ 3,800,000

Summary of significant accoun_6

Summary of significant accounting policies - Reconciliation of cash (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 158,461	$ 288,028
Restricted cash included in deposits and other assets	7,500	7,500
Total Cash, cash equivalents and restricted cash per statement of cash flows	$ 165,961	$ 295,528	$ 136,094	$ 169,498

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020USD ($)ft²Termoperating_lease	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)ft²Termoperating_lease	Jun. 30, 2019USD ($)	May 01, 2020ft²	Dec. 31, 2019ft²
Lessee, Lease, Description [Line Items]
Number of operating leases | operating_lease	3		3
Operating lease, expense	$ 2,600	$ 1,100	$ 5,000	$ 2,100
Renewal Term ( in years )	10 years		10 years
Aggregate rent, Initial term	$ 37,504		$ 37,504
2020 (excludes the six months ended June 30, 2020)	3,719		3,719
2021	6,667		6,667
2022	6,314		6,314
Fixed lease cost	1,970	835	4,089	1,647
Research and development	$ 176,525	$ 59,979	$ 266,632	$ 112,544
MassBio | Finance Lease
Lessee, Lease, Description [Line Items]
Lessee, Finance Lease, Term of Contract	12 years 6 months		12 years 6 months
Research and development	$ 41,200		$ 41,200
Minimum
Lessee, Lease, Description [Line Items]
Term of Contract ( in years )	3 months 18 days		3 months 18 days
Maximum
Lessee, Lease, Description [Line Items]
Term of Contract ( in years )	6 years 10 months 24 days		6 years 10 months 24 days
New Building
Lessee, Lease, Description [Line Items]
Area of real estate property | ft²	75,000		75,000
Renewal Term ( in years )	5 years		5 years
Hopewell Campus
Lessee, Lease, Description [Line Items]
Term of Contract ( in years )	15 years		15 years
Area of real estate property | ft²	220,500		220,500			185,000
Number of terms | Term	2		2
Aggregate rent, Initial term	$ 111,500		$ 111,500
Percent of market rate	95.00%		95.00%
Mountainview
Lessee, Lease, Description [Line Items]
2020 (excludes the six months ended June 30, 2020)	$ 900		$ 900
2021	1,800		1,800
2022	$ 1,400		$ 1,400
Bridgewater [Member]
Lessee, Lease, Description [Line Items]
Lease, Area | ft²					59,000

Leases - Lease costs (Details)

Leases - Lease costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Leases [Abstract]
Fixed lease cost	$ 1,970	$ 835	$ 4,089	$ 1,647
Variable lease cost	507	161	734	304
Short-term lease cost	88	88	165	141
Total operating lease cost	$ 2,565	$ 1,084	$ 4,988	$ 2,092

Leases - Balance sheet (Details

Leases - Balance sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease ROU asset	$ 29,475	$ 13,693
Operating lease liabilities- current	4,868	5,153
Operating lease liabilities- noncurrent	25,510	9,018
Total operating lease liability	$ 30,378	$ 14,171

Leases - Supplemental lease ter

Leases - Supplemental lease terms (Details)	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
Weighted-average remaining lease terms - operating leases (years)	5 years 10 months 13 days	3 years 4 months 17 days
Weighted-average discount rate - operating leases	6.77%	7.33%
Weighted-average remaining lease terms - finance lease (years)	12 years 6 months
Weighted-average discount rate - finance lease	7.80%

Leases - Lease payments (Detail

Leases - Lease payments (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Leases [Abstract]
2020 (excludes the six months ended June 30, 2020)	$ 3,719
2021	6,667
2022	6,314
2023	5,960
2024 and thereafter	14,844
Total lease payments	37,504
Less: Imputed Interest expense	7,126
Total	30,378	$ 14,171
2020 (excludes the six months ended June 30, 2020)	3,000
2021	3,000
2022	3,000
2023	3,000
2024 and thereafter	27,000
Total lease payments	39,000
Less: Imputed Interest expense	12,789
Total	$ 26,211	$ 0

Leases - Cash flow (Details)

Leases - Cash flow (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Leases [Abstract]
Operating cash flows from operating leases	$ 3,414	$ 1,508
Financing cash flows from finance lease	15,000	0
Right-of-use assets obtained in exchange for operating lease obligations	18,117	11,643
Right-of-use assets obtained in exchange for finance lease obligations	$ 41,212	$ 0

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($) $ in Thousands	May 29, 2020	Jun. 30, 2020	Jun. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Payments for asset acquisitions, share, value		$ 42,869	$ 42,869
Censa [Member]
Finite-Lived Intangible Assets [Line Items]
Payments for asset acquisitions	$ 15,000
Payments for asset acquisitions, upfront payment	10,400
Payments for asset acquisitions, net assets	$ 4,600
Payments for asset acquisitions, shares (in shares)	845,364
Payments for asset acquisitions, share, value	$ 42,900
Consideration for asset acquisitions	$ 15,000
Equity Interest Issued, number of shares (in shares)	42,900,000
Asset acquisition, transaction costs	$ 700
Asset acquisition, consideration transferred	58,600
Asset acquisition, cash	3,800
Asset acquisition, other assets	800
Asset acquisition, in-process research and development	54,000
Asset acquisition, research and development expense	53,300
Asset acquisition, selling, general And administrative expense	700
Asset acquisition, milestone, amount	217,500
Asset acquisition, development and regulatory milestones	109,000
Asset acquisition, net sales milestone	160,000
Asset acquisition, initial milestone	30,000
Other Research and Development Expense	$ 300

Acquisitions - Preliminary Allo

Acquisitions - Preliminary Allocation of purchase price (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 82,341	$ 82,341

Fair value of financial instr_3

Fair value of financial instruments and marketable securities - Narrative (Details)	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2020USD ($)	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)$ / sharesshares	Jun. 30, 2019USD ($)	Jun. 29, 2020USD ($)	Apr. 29, 2020USD ($)	Dec. 31, 2019USD ($)	May 31, 2019USD ($)$ / shares	Dec. 31, 2018USD ($)	Aug. 31, 2015USD ($)$ / shares
Financial assets and liabilities measured at fair value on recurring basis
Marketable Securities, Realized Gain (Loss)		$ 200,000		$ 200,000
Deferred consideration payable		2,384,000		2,384,000				$ 40,000,000
Unrealized gain (loss) on equity investment				(1,600,000)	$ 129,000
Investment In MRI		$ 4,600,000		4,600,000
Purchase of convertible debt investment	$ 10,000,000			$ 10,000,000	0
Conversion price per share (in dollars per share) | $ / shares		$ 6		$ 6
Debt instrument, convertible, period				5 years
Unrealized loss				$ 700,000
Marketable securities		$ 340,430,000		340,430,000				398,535,000
Non-cash stock consideration, acquisition				42,869,000	0
Operating Expenses		262,512,000	$ 124,280,000	423,762,000	247,003,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset		(7,680,000)	(5,300,000)	$ (8,580,000)	(26,460,000)
Debt Securities, Available-for-sale, Unrealized Gain		$ 2,100,000
Common stock
Financial assets and liabilities measured at fair value on recurring basis
Issuance of common stock related to rights exchange (in shares) | shares		2,821,176		2,821,176
Commitments
Financial assets and liabilities measured at fair value on recurring basis
Liability value		$ 136,100,000	277,400,000	$ 136,100,000	277,400,000			290,500,000		$ 257,040,000
SARs
Financial assets and liabilities measured at fair value on recurring basis
Liability value		0	$ 1,960,000	0	$ 1,960,000			3,186,000		$ 3,814,000
3.00% Convertible senior notes due 2022 | Convertible debt
Financial assets and liabilities measured at fair value on recurring basis
Principal		150,000,000		150,000,000				150,000,000			$ 150,000,000
Interest rate ( as a percent )											3.00%
Fair value of convertible notes		175,200,000		175,200,000				171,200,000
Conversion price per share (in dollars per share) | $ / shares											$ 56.34
1.50% Convertible senior notes due 2026 | Convertible debt
Financial assets and liabilities measured at fair value on recurring basis
Principal		$ 287,500,000		$ 287,500,000				$ 287,500,000
Interest rate ( as a percent )		1.50%		1.50%				1.50%
Fair value of convertible notes		$ 343,800,000		$ 343,800,000				$ 335,000,000
Conversion price per share (in dollars per share) | $ / shares		$ 52.52		$ 52.52
Agilis
Financial assets and liabilities measured at fair value on recurring basis
Development milestone payments which the entity is obligated to pay		$ 40,000,000		$ 40,000,000			$ 40,000,000
Net sales amount							$ 150,000,000
Deferred consideration payable		2,400,000		2,400,000
Non-cash stock consideration, acquisition		36,900,000
Milestone Payment Obligations						$ 174,000,000
Gain Of Settlement, Development Milestones		700,000
Loss Of Settlement, Regulatory Milestones		11,300,000
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset		1,000,000
Contingent Consideration, Transaction Fees		$ 2,000,000		$ 2,000,000
Agilis | Common stock
Financial assets and liabilities measured at fair value on recurring basis
Issuance of common stock related to rights exchange (in shares) | shares				2,821,176
Agilis | Minimum
Financial assets and liabilities measured at fair value on recurring basis
Product sales		2.00%		2.00%			2.00%
Development milestone payments which the entity is obligated to pay						37,600,000
Agilis | Maximum
Financial assets and liabilities measured at fair value on recurring basis
Product sales		6.00%		6.00%			6.00%
Development milestone payments which the entity is obligated to pay		$ 60,000,000		$ 60,000,000		$ 40,000,000
Priority review voucher amount				535,000,000
Net sales amount		150,000,000		150,000,000
Non-collaborative Arrangement Transactions | Agilis
Financial assets and liabilities measured at fair value on recurring basis
Development milestone payments which the entity is obligated to pay		40,000,000		40,000,000
Recurring basis | Total
Financial assets and liabilities measured at fair value on recurring basis
Estimated fair value of deferred consideration payable		2,384,000		2,384,000				40,000,000
Liability value		89,600,000		89,600,000				65,800,000
Marketable securities								$ 398,535,000
Common stock
Financial assets and liabilities measured at fair value on recurring basis
Shares owned									$ 4,000,000
Fair value of shares (in dollars per share) | $ / shares									$ 3.10
Unrealized gain (loss) on equity investment		100,000		1,600,000
Deferred consideration payable | Recurring basis | Total
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities		$ 9,251,000		$ 9,251,000
Development and Regulatory Milestone | Probability of Success [Member] | Minimum | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.25		0.25				0.25
Development and Regulatory Milestone | Probability of Success [Member] | Maximum | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.94		0.94				0.94
Development and Regulatory Milestone | Probability of Success [Member] | Weighted Average [Member] | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.43		0.43
Development and Regulatory Milestone | Agilis
Financial assets and liabilities measured at fair value on recurring basis
Liability value		$ 136,100,000		$ 136,100,000				$ 290,500,000
Development and Regulatory Milestone | Agilis | Measurement Input, Discount Rate | Minimum | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input								0.022
Development and Regulatory Milestone | Agilis | Measurement Input, Discount Rate | Maximum | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input								0.047
Development and Regulatory Milestone | Agilis | Measurement Input, Discount Rate | Weighted Average [Member] | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.054		0.054
Liability, Net Sales Milestones and Royalties [Member] | Probability of Success [Member] | Minimum | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.25		0.25				0.25
Liability, Net Sales Milestones and Royalties [Member] | Probability of Success [Member] | Maximum | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.94		0.94				0.89
Liability, Net Sales Milestones and Royalties [Member] | Probability of Success [Member] | Weighted Average [Member] | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.50		0.50
Liability, Net Sales Milestones and Royalties [Member] | Agilis
Financial assets and liabilities measured at fair value on recurring basis
Liability value		$ 89,600,000		$ 89,600,000				$ 65,800,000
Liability, Net Sales Milestones and Royalties [Member] | Agilis | Measurement Input, Discount Rate | Commitments
Financial assets and liabilities measured at fair value on recurring basis
Alternative Investment, Measurement Input		0.120		0.120				0.145

Fair value of financial instr_4

Fair value of financial instruments and marketable securities - Hierarchy (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	$ 340,430	$ 398,535
Contingent consideration payable	225,700	356,300
Significant unobservable inputs (level 3)
Financial assets and liabilities measured at fair value on recurring basis
Contingent consideration payable- net sales milestones and royalties	89,600
Recurring basis | Total
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities		398,535
Equity investment in ClearPoint	4,594	6,194
Stock appreciation rights liability		3,186
Deferred consideration payable	2,384	40,000
Contingent consideration payable	136,100	290,500
Contingent consideration payable- net sales milestones and royalties	89,600	65,800
Recurring basis | Quoted prices in active markets for identical assets (level 1)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities		0
Equity investment in ClearPoint	4,594	6,194
Stock appreciation rights liability		0
Deferred consideration payable	0	0
Contingent consideration payable	0	0
Contingent consideration payable- net sales milestones and royalties	0	0
Recurring basis | Significant other observable inputs (level 2)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities		398,535
Equity investment in ClearPoint	0	0
Stock appreciation rights liability		0
Deferred consideration payable	2,384	40,000
Contingent consideration payable	0	0
Contingent consideration payable- net sales milestones and royalties	0	0
Recurring basis | Significant unobservable inputs (level 3)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities		0
Equity investment in ClearPoint	0	0
Stock appreciation rights liability		3,186
Deferred consideration payable	0	0
Contingent consideration payable	136,100	$ 290,500
Marketable securities | Recurring basis | Total
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	340,430
Marketable securities | Recurring basis | Quoted prices in active markets for identical assets (level 1)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	0
Marketable securities | Recurring basis | Significant other observable inputs (level 2)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	340,430
Marketable securities | Recurring basis | Significant unobservable inputs (level 3)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	0
Deferred consideration payable | Recurring basis | Total
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	9,251
Deferred consideration payable | Recurring basis | Quoted prices in active markets for identical assets (level 1)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	0
Deferred consideration payable | Recurring basis | Significant other observable inputs (level 2)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	9,251
Deferred consideration payable | Recurring basis | Significant unobservable inputs (level 3)
Financial assets and liabilities measured at fair value on recurring basis
Marketable securities	$ 0

Fair value of financial instr_5

Fair value of financial instruments and marketable securities - Available for sale (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 2	$ 28
Amortized Cost	337,021	397,776
Gross Unrealized, Gain	3,411	787
Gross Unrealized, Loss	(2)	(28)
Fair Value	340,430	398,535
Securities in an unrealized loss position less than 12 months	9,196	95,990
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Securities in an unrealized loss position greater than 12 months	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	2	28
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	9,196	95,990
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	53,638	157,936
Gross Unrealized, Gain	178	162
Gross Unrealized, Loss	0	0
Fair Value	53,816	158,098
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		20
Amortized Cost	221,068	188,778
Gross Unrealized, Gain	2,882	576
Gross Unrealized, Loss	0	(20)
Fair Value	223,950	189,334
Securities in an unrealized loss position less than 12 months		71,779
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0
Securities in an unrealized loss position greater than 12 months		0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss		20
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value		71,779
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1	8
Amortized Cost	44,492	51,062
Gross Unrealized, Gain	332	49
Gross Unrealized, Loss	(1)	(8)
Fair Value	44,823	51,103
Securities in an unrealized loss position less than 12 months	594	24,211
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0	0
Securities in an unrealized loss position greater than 12 months	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1	8
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	594	$ 24,211
Government obligations
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1
Amortized Cost	17,823
Gross Unrealized, Gain	19
Gross Unrealized, Loss	(1)
Fair Value	17,841
Securities in an unrealized loss position less than 12 months	8,602
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Securities in an unrealized loss position greater than 12 months	0
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	1
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	$ 8,602

Fair value of financial instr_6

Fair value of financial instruments and marketable securities - Fair Value Measurement Inputs and Valuation Techniques (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Level 3 roll forward
Additions	$ 0	$ 0
Significant unobservable inputs (level 3)
Level 3 roll forward
Contingent consideration payable- net sales milestones and royalties	89,600
SARs
Level 3 roll forward
Contingent consideration payable- net sales milestones and royalties	0	1,960	$ 3,186	$ 3,814
Change in fair value	0	1,961
Payments	(3,186)	(3,815)
Commitments
Level 3 roll forward
Contingent consideration payable- net sales milestones and royalties	136,100	277,400	290,500	257,040
Additions	0	0
Change in fair value	(15,220)	20,360
Payments	0	0
Agilis | Significant unobservable inputs (level 3)
Level 3 roll forward
Contingent consideration payable- net sales milestones and royalties			65,800
Liability, Net Sales Milestones and Royalties [Member] | Agilis
Level 3 roll forward
Contingent consideration payable- net sales milestones and royalties	89,600		65,800
Liability, Net Sales Milestones and Royalties [Member] | Agilis | Significant unobservable inputs (level 3)
Level 3 roll forward
Contingent consideration payable- net sales milestones and royalties	89,600	58,800	$ 65,800	$ 53,200
Additions	0	0
Change in fair value	23,800	5,600
Payments	$ 0	$ 0

Fair value of financial instr_7

Fair value of financial instruments and marketable securities - Unrealized Loss Positions (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Unrealized losses
Securities in an unrealized loss position less than 12 months	$ (2)	$ (28)
Securities in an unrealized loss position greater than 12 months	0	0
Total	(2)	(28)
Fair Value
Securities in an unrealized loss position less than 12 months	9,196	95,990
Securities in an unrealized loss position greater than 12 months	0	0
Total	9,196	95,990
Corporate debt securities
Unrealized losses
Securities in an unrealized loss position less than 12 months		(20)
Securities in an unrealized loss position greater than 12 months		0
Total		(20)
Fair Value
Securities in an unrealized loss position less than 12 months		71,779
Securities in an unrealized loss position greater than 12 months		0
Total		71,779
Asset-backed securities
Unrealized losses
Securities in an unrealized loss position less than 12 months	(1)	(8)
Securities in an unrealized loss position greater than 12 months	0	0
Total	(1)	(8)
Fair Value
Securities in an unrealized loss position less than 12 months	594	24,211
Securities in an unrealized loss position greater than 12 months	0	0
Total	594	$ 24,211
Government obligations
Unrealized losses
Securities in an unrealized loss position less than 12 months	(1)
Securities in an unrealized loss position greater than 12 months	0
Total	(1)
Fair Value
Securities in an unrealized loss position less than 12 months	8,602
Securities in an unrealized loss position greater than 12 months	0
Total	$ 8,602

Fair value of financial instr_8

Fair value of financial instruments and marketable securities - Marketable securities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	$ 255,587	$ 342,418
Total Marketable securities, More Than 12 Months	84,843	56,117
Commercial paper
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	53,816	158,098
Total Marketable securities, More Than 12 Months	0	0
Corporate debt securities
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	168,250	139,596
Total Marketable securities, More Than 12 Months	55,700	49,738
Asset-backed securities
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	26,320	44,724
Total Marketable securities, More Than 12 Months	18,503	$ 6,379
Government obligations
Marketable securities on the balance sheet
Total Marketable securities, Less Than 12 Months	7,201
Total Marketable securities, More Than 12 Months	$ 10,640

Fair value of financial instr_9

Fair value of financial instruments and marketable securities - Warrants and SARs (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2019USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)	Dec. 31, 2019USD ($)$ / shares
Changes in the fair value of warrant liability and SARs liability
Additions		$ 0	$ 0
Weighted-average discount rate - finance lease		7.80%
SARs
Changes in the fair value of warrant liability and SARs liability
Beginning Balance	$ 3,814	$ 3,186	3,814
Change in fair value		0	1,961
Payments		(3,186)	(3,815)
Rights Exchange settlement		0
Ending Balance		0	1,960
Commitments
Changes in the fair value of warrant liability and SARs liability
Beginning Balance	$ 257,040	290,500	257,040
Additions		0	0
Change in fair value		(15,220)	20,360
Payments		0	0
Rights Exchange settlement		(139,180)
Ending Balance		136,100	277,400
SARs
Changes in the fair value of warrant liability and SARs liability
Beginning Balance		$ 3,186
Measurement Input, Option Volatility | SARs
Fair value of warrant liability
Alternative Investment, Measurement Input				28.93
Measurement Input, Risk Free Interest Rate | SARs
Fair value of warrant liability
Alternative Investment, Measurement Input				0.19
Measurement Input, Expected Term | SARs
Fair value of warrant liability
Expected term (in years)	3 days
Minimum | SARs
Fair value of warrant liability
Alternative Investment, Measurement Input | $ / shares				6.76
Maximum | SARs
Fair value of warrant liability
Alternative Investment, Measurement Input | $ / shares				30.86
Common stock | Measurement Input, Share Price | SARs
Fair value of warrant liability
Alternative Investment, Measurement Input | $ / shares				48.03
Liability, Net Sales Milestones and Royalties [Member] | Minimum | Probability of Success [Member] | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input		0.25		0.25
Liability, Net Sales Milestones and Royalties [Member] | Maximum | Probability of Success [Member] | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input		0.94		0.89
Development and Regulatory Milestone | Minimum | Probability of Success [Member] | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input		0.25		0.25
Development and Regulatory Milestone | Maximum | Probability of Success [Member] | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input		0.94		0.94
Agilis | Liability, Net Sales Milestones and Royalties [Member]
Changes in the fair value of warrant liability and SARs liability
Beginning Balance		$ 65,800
Ending Balance		$ 89,600
Agilis | Liability, Net Sales Milestones and Royalties [Member] | Measurement Input, Discount Rate | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input		0.120		0.145
Agilis | Liability, Net Sales Milestones and Royalties [Member] | Minimum | Sales Milestones | Commitments
Fair value of warrant liability
Alternative Investment, Milestone				$ 0
Agilis | Liability, Net Sales Milestones and Royalties [Member] | Minimum | Percentage of Sales for Royalties | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input		0.02		0.02
Agilis | Liability, Net Sales Milestones and Royalties [Member] | Minimum | Potential Net Sales Milestones [Domain] | Commitments
Fair value of warrant liability
Alternative Investment, Milestone		$ 0
Agilis | Liability, Net Sales Milestones and Royalties [Member] | Maximum | Sales Milestones | Commitments
Fair value of warrant liability
Alternative Investment, Milestone				$ 150,000
Agilis | Liability, Net Sales Milestones and Royalties [Member] | Maximum | Percentage of Sales for Royalties | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input		0.06		0.06
Agilis | Liability, Net Sales Milestones and Royalties [Member] | Maximum | Potential Net Sales Milestones [Domain] | Commitments
Fair value of warrant liability
Alternative Investment, Milestone		$ 150,000
Agilis | Development and Regulatory Milestone
Changes in the fair value of warrant liability and SARs liability
Beginning Balance		290,500
Ending Balance		136,100
Agilis | Development and Regulatory Milestone | Minimum | Development and Regulatory Milestone | Commitments
Fair value of warrant liability
Alternative Investment, Milestone		$ 0		$ 0
Agilis | Development and Regulatory Milestone | Minimum | Measurement Input, Discount Rate | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input				0.022
Changes in the fair value of warrant liability and SARs liability
Weighted-average discount rate - finance lease		4.60%
Agilis | Development and Regulatory Milestone | Maximum | Development and Regulatory Milestone | Commitments
Fair value of warrant liability
Alternative Investment, Milestone		$ 381,000		$ 555,000
Agilis | Development and Regulatory Milestone | Maximum | Measurement Input, Discount Rate | Commitments
Fair value of warrant liability
Alternative Investment, Measurement Input				0.047
Changes in the fair value of warrant liability and SARs liability
Weighted-average discount rate - finance lease		6.10%
Significant unobservable inputs (level 3)
Changes in the fair value of warrant liability and SARs liability
Ending Balance		$ 89,600
Significant unobservable inputs (level 3) | Agilis
Changes in the fair value of warrant liability and SARs liability
Beginning Balance		65,800
Significant unobservable inputs (level 3) | Agilis | Liability, Net Sales Milestones and Royalties [Member]
Changes in the fair value of warrant liability and SARs liability
Beginning Balance	$ 53,200	65,800	53,200
Additions		0	0
Change in fair value		23,800	5,600
Payments		0	0
Rights Exchange settlement		0
Ending Balance		$ 89,600	$ 58,800

Other comprehensive income (l_3

Other comprehensive income (loss) and accumulated other comprehensive items - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Other comprehensive income (loss) and accumulated other comprehensive items
Balance at the beginning of the period	$ 528,734	$ 594,330
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications	(8,031)	568
Amounts reclassified from other comprehensive items	0	0
Other comprehensive income (loss)	(8,031)	568
Balance at the end of the period	572,494	572,494
Unrealized Gains/(Losses) On Marketable Securities, net of tax
Other comprehensive income (loss) and accumulated other comprehensive items
Balance at the beginning of the period	692	755
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications	2,718	2,655
Amounts reclassified from other comprehensive items	0	0
Other comprehensive income (loss)	2,718	2,655
Balance at the end of the period	3,410	3,410
Foreign Currency Translation
Other comprehensive income (loss) and accumulated other comprehensive items
Balance at the beginning of the period	(2,677)	(11,339)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications	(10,749)	(2,087)
Amounts reclassified from other comprehensive items	0	0
Other comprehensive income (loss)	(10,749)	(2,087)
Balance at the end of the period	(13,426)	(13,426)
AOCI Attributable to Parent
Other comprehensive income (loss) and accumulated other comprehensive items
Balance at the beginning of the period	(1,985)	(10,584)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at the end of the period	$ (10,016)	$ (10,016)

Accounts payable and accrued _3

Accounts payable and accrued expenses - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Employee compensation, benefits, and related accruals	$ 24,861	$ 38,889
Consulting and contracted research	13,452	12,969
Professional fees	3,295	3,562
Sales allowance and other costs	45,848	41,155
Sales rebates and royalties	56,870	42,997
Accounts payable	15,465	10,324
Other	4,585	9,380
Accounts payable and accrued expenses	$ 164,376	$ 159,276

Capitalization - Narrative (Det

Capitalization - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	May 29, 2020	Aug. 31, 2019	Jun. 30, 2020	Jun. 30, 2020	Apr. 29, 2020
Warrants
Consideration received on transaction			$ 5,400	$ 19,000
Number of shares issued in transaction (in shares)			106,309	368,514
Payments for asset acquisitions, share, value			$ 42,869	$ 42,869
Rights Exchange Agreement [Member]
Warrants
Shares to issue under Rights Exchange Agreement					2,821,176
Payments for asset acquisitions, share, value				$ 150,500
Censa [Member]
Warrants
Payments for asset acquisitions, shares (in shares)	845,364
Payments for asset acquisitions, share, value	$ 42,900
Maximum
Warrants
Consideration received on transaction		$ 125,000
Weighted Average [Member]
Warrants
Sale of stock, weighted average price per share (in USD per share)			$ 53.08	$ 52.89

Net loss per share - Numerator

Net loss per share - Numerator and Denominator (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator
Net loss	$ (181,427)	$ (41,789)	$ (294,114)	$ (113,902)
Denominator
Denominator for basic and diluted net loss per share (in shares)	65,150,780	55,912,748	63,769,958	57,113,141
Net loss per share:
Basic and diluted (in dollars per share)	$ (2.78)	$ (0.75)	$ (4.61)	$ (1.99)

Net loss per share - Antidiluti

Net loss per share - Antidilutive (Details) - shares	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Net loss per share
Total shares excluded from calculation (in shares)	12,891,606	11,518,303
Stock Options
Net loss per share
Total shares excluded from calculation (in shares)	11,954,684	10,853,301
Unvested restricted stock awards and units
Net loss per share
Total shares excluded from calculation (in shares)	936,922	665,002

Stock award plan - Narrative (D

Stock award plan - Narrative (Details) - USD ($)	Mar. 05, 2013	Jan. 31, 2020	Jun. 30, 2016	May 31, 2016	May 31, 2013	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2016
Stock option plan
Share-based compensation expense						$ 16,910,000	$ 10,920,000	$ 32,130,000	$ 20,184,000
Unrecognized compensation cost						$ 187,200,000		$ 187,200,000
Weighted average remaining service period for recognition of unrecognized compensation cost								3 years 29 days
Common stock
Stock option plan
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant						914,406		914,406
Unvested restricted stock
Stock option plan
Grants in period (in shares)								589,070
Stock option
Stock option plan
Granted (in shares)								2,515,200
Inducement grants for non-statutory stock options (in shares)								542,450
Expected dividend yield (as a percent)								0.00%
Weighted average grant date fair value (in dollars per share)								$ 36.95
Expected term (in years)								5 years 9 months
Stock option | Maximum
Stock option plan
Risk-free interest rate (as a percent)								1.45%
Expected volatility (as a percent)								89.31%
Stock option | Minimum
Stock option plan
Risk-free interest rate (as a percent)								0.40%
Expected volatility (as a percent)								87.50%
SARs
Stock option plan
Granted (in shares)				897,290
Vested (in shares)								132,136
Stock appreciation rights liability						$ 0		$ 0
2013 Stock Incentive Plan
Stock option plan
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	0
2013 Stock Incentive Plan | Common stock
Stock option plan
Number of shares authorized (in shares)	739,937
2013 Stock Incentive Plan | Unvested restricted stock
Stock option plan
Grants in period (in shares)	735,324
2013 Stock Incentive Plan | Stock option
Stock option plan
Granted (in shares)	4,613
2009 Equity and Long Term Incentive Plan
Stock option plan
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant						0		0
Number of additional shares authorized (in shares)					2,500,000
2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan | Common stock
Stock option plan
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant					122,296
2009 Equity and Long Term Incentive Plan and 2013 Stock Incentive Plan | 1998 Employee, Director and Consultant Stock Option Plan | Common stock | Maximum
Stock option plan
Number of shares subject to outstanding awards (in shares)					3,040,444
2013 Long Term Incentive Plan | Minimum
Stock option plan
Share based Compensation Arrangement by Share based Payment Award Number of Shares Authorized Annual Increase Number					2,500,000
Annual increase in the number of shares outstanding on the first day of the fiscal year					4.00%
2020 inducement stock incentive plan [Member] | Common stock
Stock option plan
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant						442,880		442,880
Share based Compensation Arrangement by Share based Payment Award Number of Shares Authorized Annual Increase Number		1,000,000
Employee Stock [Member]
Stock option plan
Number of shares authorized (in shares)										1,000,000
Share-based compensation expense						$ 300,000		$ 700,000
Award requisite service period			6 months
Purchase price of common stock, percent			85.00%
Employee stock purchase plan, voting percentage limit			5.00%

Stock award plan - Share Base C

Stock award plan - Share Base Compensation (Details) - Stock option - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2020
Number of options
Outstanding at the beginning of the period (in shares)	11,043,939
Granted (in shares)	2,515,200
Exercised (in shares)	(1,034,288)
Forfeited/Cancelled (in shares)	(570,167)
Outstanding at the end of the period (in shares)	11,954,684
Vested or Expected to vest at the end of the period (in shares)	5,690,848
Exercisable at the end of the period (in shares)	5,512,252
Weighted- average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 31.67
Granted (in dollars per share)	50.98
Exercised (in dollars per share)	24.21
Forfeited/Cancelled (in dollars per share)	42.27
Outstanding at the end of the period (in dollars per share)	35.84
Vested or Expected to vest at the end of the period (in dollars per share)	39.16
Exercisable at the end of the period (in dollars per share)	$ 31.61
Weighted- average remaining contractual term
Outstanding at the end of the period	7 years 5 months 23 days
Vested or Expected to vest at the end of the period	8 years 10 months 9 days
Exercisable at the end of the period	5 years 10 months 6 days
Aggregate intrinsic value (in thousands)
Outstanding at the end of the period (in dollars)	$ 183,488
Vested or Expected to vest at the end of the period (in dollars)	66,986
Exercisable at the end of the period (in dollars)	$ 110,222
Valuation assumptions
Expected term (in years)	5 years 9 months
Minimum
Valuation assumptions
Risk-free interest rate (as a percent)	0.40%
Expected volatility (as a percent)	87.50%
Maximum
Valuation assumptions
Risk-free interest rate (as a percent)	1.45%
Expected volatility (as a percent)	89.31%

Stock award plan - Restricted S

Stock award plan - Restricted Stock (Details) - Unvested restricted stock	6 Months Ended
	Jun. 30, 2020$ / sharesshares
Number of Shares
Balance at the beginning of the period (in shares) | shares	642,419
Granted (in shares) | shares	589,070
Vested (in shares) | shares	(229,076)
Forfeited (in shares) | shares	(65,491)
Balance at the end of the period (in shares) | shares	936,922
Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share) | $ / shares	$ 24.50
Granted (in dollars per share) | $ / shares	49.67
Vested (in dollars per share) | $ / shares	23.53
Forfeited (in dollars per share) | $ / shares	36.11
Balance at the end of the period (in dollars per share) | $ / shares	$ 39.97

Stock award plan - Share-based

Stock award plan - Share-based compensation expense (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock option plan
Share-based compensation expense		$ 16,910	$ 10,920	$ 32,130	$ 20,184
Research and development
Stock option plan
Share-based compensation expense		8,562	5,516	16,741	10,203
Selling, general and administrative
Stock option plan
Share-based compensation expense		$ 8,348	$ 5,404	$ 15,389	$ 9,981
Common stock
Stock option plan
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		914,406		914,406
Common stock | 2020 inducement stock incentive plan [Member]
Stock option plan
Share based Compensation Arrangement by Share based Payment Award Number of Shares Authorized Annual Increase Number	1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		442,880		442,880

Debt - Narrative (Details)

Debt - Narrative (Details)	May 05, 2017USD ($)	Sep. 30, 2019USD ($)day	May 31, 2017USD ($)	Aug. 31, 2015USD ($)$ / shares	Jun. 30, 2020USD ($)$ / shares	Jun. 30, 2020USD ($)$ / shares	Dec. 31, 2019USD ($)
Long-term debt
Long-term debt					$ 297,029,000	$ 297,029,000	$ 293,859,000
Current portion of long-term debt					$ 18,333,000	18,333,000	20,000,000
Debt instrument additional amount available for repurchase						$ 37,500,000
Conversion price per share (in dollars per share) | $ / shares					$ 6	$ 6
Convertible debt | 3.00% Convertible senior notes due 2022
Long-term debt
Net carrying amount					$ 126,730,000	$ 126,730,000	121,985,000
Debt principal amount				$ 150,000,000	$ 150,000,000	$ 150,000,000	150,000,000
Interest rate ( as a percent )				3.00%
Net proceeds from issuance of convertible notes				$ 145,400,000
Trading days, number | day		20
Stock price trigger		130.00%
Business days, period		5 days
Consecutive trading-day period		5 days
Maximum product of the closing sale price of shares of the Company's common stock and the applicable conversion rate for such trading day					98.00%	98.00%
Conversion ratio				17.7487
Conversion price per share (in dollars per share) | $ / shares				$ 56.34
Convertible instruments principal and unpaid interest payable upon events of default		100.00%
Minimum percentage of principal held by convertible debt instrument holders required to issue notice for declaration of principal and unpaid interest payable upon events of default		25.00%
Term of the convertible notes		7 years		7 years
Adjustments to additional paid in capital, equity component of convertible debt				$ 57,500,000
Net deferred tax liability in connection with convertible notes				$ 22,300,000
Fair value of convertible notes					$ 175,200,000	$ 175,200,000	171,200,000
Remaining contractual life of the convertible notes						2 years 1 month 6 days
Convertible debt | 3.00% Convertible senior notes due 2022 | Redemption on or after August 20, 2018
Long-term debt
Trading days, number | day		19
Consecutive trading days, period | day		30
Stock price trigger		130.00%
Redemption price		100.00%
Sinking fund					0	$ 0
Convertible debt | 1.50% Convertible senior notes due 2026
Long-term debt
Net carrying amount					170,304,000	170,304,000	163,583,000
Debt principal amount					$ 287,500,000	$ 287,500,000	$ 287,500,000
Interest rate ( as a percent )					1.50%	1.50%	1.50%
Net proceeds from issuance of convertible notes						$ 279,300,000
Conversion ratio		19.0404
Conversion price per share (in dollars per share) | $ / shares					$ 52.52	$ 52.52
Term of the convertible notes					6 years 2 months 12 days
Adjustments to additional paid in capital, equity component of convertible debt		$ 123,000,000
Net deferred tax liability in connection with convertible notes					$ 25,300,000	$ 25,300,000
Fair value of convertible notes					343,800,000	343,800,000	$ 335,000,000
MidCap Financial Trust
Long-term debt
Line of credit facility, maximum borrowing capacity			$ 60,000,000
Proceeds from lines of credit	$ 40,000,000
Line of credit facility, additional capacity available, net product revenue threshold			20,000,000
Debt issuance costs			$ 400,000
Repayments of debt						21,700,000
Current portion of long-term debt					$ 18,300,000	$ 18,300,000
Debt instrument, floor interest rate			1.00%
Debt instrument, basis spread on variable rate			6.15%
Debt instrument, interest payment period			24 months

Debt - Convertible Notes (Detai

Debt - Convertible Notes (Details) - Convertible debt - USD ($)	Jun. 30, 2020	Dec. 31, 2019	Aug. 31, 2015
3.00% Convertible senior notes due 2022
Long-term debt
Principal	$ 150,000,000	$ 150,000,000	$ 150,000,000
Less: Debt issuance costs	(1,104,000)	(1,329,000)
Less: Debt discount, net	(22,166,000)	(26,686,000)
Net carrying amount	126,730,000	121,985,000
1.50% Convertible senior notes due 2026
Long-term debt
Principal	287,500,000	287,500,000
Less: Debt issuance costs	(4,319,000)	(4,567,000)
Less: Debt discount, net	(112,877,000)	(119,350,000)
Net carrying amount	$ 170,304,000	$ 163,583,000

Debt - Interest Expense (Detail

Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Long-term debt
Amortization of debt issuance costs			$ 510	$ 280
Convertible debt | 3.00% Convertible senior notes due 2022
Long-term debt
Contractual interest expense	$ 1,125	$ 1,131	2,244	2,241
Amortization of debt issuance costs	114	103	225	202
Amortization of debt discount	2,295	2,074	4,520	4,055
Total	$ 3,534	$ 3,308	$ 6,989	$ 6,498
Effective interest rate of the liability component	11.00%	11.00%	11.00%	11.00%
Convertible debt | 1.50% Convertible senior notes due 2026
Long-term debt
Contractual interest expense	$ 1,066		$ 2,142
Amortization of debt issuance costs	124		248
Amortization of debt discount	3,239		6,473
Total	$ 4,429		$ 8,863
Effective interest rate of the liability component	10.20%		10.20%

Commitments and contingencies -

Commitments and contingencies - Narrative (Details) - USD ($) $ in Millions	Jun. 29, 2020	Apr. 29, 2020	Jun. 30, 2020	May 29, 2020	Dec. 31, 2019	Sep. 30, 2019	Apr. 20, 2017	Sep. 30, 2016
Akcea
Other Commitments [Abstract]
Upfront licensing fee			$ 12
Akcea | Maximum
Other Commitments [Abstract]
Milestone payments					$ 4
Censa [Member]
Other Commitments [Abstract]
Asset acquisition, milestone, amount				$ 217.5
Asset acquisition, development and regulatory milestones				109
Asset acquisition, net sales milestone				160
Asset acquisition, initial milestone				30
Censa [Member] | Maximum
Other Commitments [Abstract]
Asset acquisition, milestone, amount				$ 217.5
Non-collaborative Arrangement Transactions | Marathon Pharmaceuticals, LLC
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay							$ 50
Non-collaborative Arrangement Transactions | Akcea
Other Commitments [Abstract]
Milestone payments			4			$ 6
Agilis
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay		$ 40	40
Net sales amount		150
Development Milestone Payment Obligations, Net of Cancellation and Forfeiture			22.4
Agilis | Rights Exchange Agreement [Member]
Other Commitments [Abstract]
Priority review voucher amount		174
Contingent Liability cancellation and forfeiture, Milestone, Potential Achievements, Priority Review Voucher Amount			174
Development Milestone Payment Obligations, Cancellation and Forfeiture		37.6	37.6
Development Milestone Payment Obligations, Net of Cancellation and Forfeiture		22.4
Contingent Liability, Cancellation and Forfeiture	$ 211.6	211.6
Contingent Liability, Milestone, Potential Achievements, Priority Review Voucher Amount, Net of Cancellation and Forfeiture		$ 361
Agilis | Maximum
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay	40		60
Priority review voucher amount			535
Net sales amount			$ 150
Product sales		6.00%	6.00%
Agilis | Maximum | Rights Exchange Agreement [Member]
Other Commitments [Abstract]
Contingent Liability, Milestone, Potential Achievements, Priority Review Voucher Amount, Net of Cancellation and Forfeiture			$ 361
Agilis | Minimum
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay	$ 37.6
Product sales		2.00%	2.00%
Agilis | Non-collaborative Arrangement Transactions
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay			$ 40
BioElectron | Maximum
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay			200
Product | Wellcome trust
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay								$ 0.8
Product | Wellcome trust | Maximum
Other Commitments [Abstract]
Development milestone payments which the entity is obligated to pay			$ 22.4

Revenue recognition - Narrative

Revenue recognition - Narrative (Details)	1 Months Ended	3 Months Ended		6 Months Ended
	Nov. 30, 2011USD ($)	Jun. 30, 2020USD ($)Number_Distributor	Jun. 30, 2019USD ($)Number_Distributor	Jun. 30, 2020USD ($)Number_Distributorsegment	Jun. 30, 2019USD ($)Number_Distributor
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Number of operating segments | segment				1
Percentage of net product sales		10.00%	10.00%	10.00%	10.00%
Number of distributors | Number_Distributor		2	2	2	2
Revenue		$ 75,239,000	$ 85,522,000	$ 143,498,000	$ 139,105,000
Performance obligations satisfied in current period		2,000,000		4,000,000
Licensing And Collaboration Agreement
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		0	100,000	100,000	100,000
Licensing And Collaboration Agreement | Research And Development Event Milestones
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognition, milestone, potential achievements	$ 135,000,000			72,500,000
Licensing And Collaboration Agreement | Sales Milestones
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue recognition, milestone, potential achievements	$ 325,000,000			325,000,000
United States
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net product revenue		36,200,000	27,600,000	63,600,000	45,400,000
Non-US
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net product revenue		$ 39,000,000	$ 57,800,000	$ 79,800,000	$ 93,000,000

Revenue recognition - Performan

Revenue recognition - Performance Obligations (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Liability		$ 11.7
Deferred consideration payable		$ 11.7
Revenue, performance obligation, period		1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Liability	$ 7.7
Deferred consideration payable	$ 7.7
Revenue, performance obligation, period	1 year

Intangible assets and goodwil_2

Intangible assets and goodwill - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Sep. 30, 2019	Apr. 20, 2017
Finite-Lived Intangible Assets [Line Items]
Useful life		7 years
Amortization of acquired intangible assets	$ 8,731		$ 6,575	$ 16,679	$ 12,652
Total allocation of IPR&D assets				576,500
Goodwill	82,341			82,341		$ 82,341
Research and development	176,525		59,979	$ 266,632	112,544
Weighted Average [Member]
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period				4 years
Akcea
Finite-Lived Intangible Assets [Line Items]
Upfront licensing fee				$ 12,000
Non-collaborative Arrangement Transactions | Akcea
Finite-Lived Intangible Assets [Line Items]
Milestone payments	4,000			$ 4,000			$ 6,000
Useful life				10 years
Emflaza asset acquisition
Finite-Lived Intangible Assets [Line Items]
Finite-Lived intangibles								$ 148,400
Milestone payments	$ 12,200		$ 8,300	$ 12,200	$ 8,300

Intangible assets and goodwil_3

Intangible assets and goodwill - Future Amortization (Details) $ in Thousands	Jun. 30, 2020USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2020	$ 17,460
2021	34,920
2022	34,920
2023	34,920
2024 and thereafter	10,094
Total	$ 132,314

Subsequent events Narrative (De

Subsequent events Narrative (Details) - Subsequent Event [Member] - USD ($) $ in Millions	Jul. 17, 2020	Jul. 01, 2020
Subsequent Event [Line Items]
Repayments of lines of credit		$ 18.4
Termination and exit fees		$ 0.6
Assigned royalty payment, percentage	42.933%
Proceeds assigned royalty payment agreement	$ 650
Assigned royalty payment, retained percentage	57.067%
Revenue recognition, milestone, potential achievements	$ 397.5
Royalty purchase agreement, termination period	60 days
Royalty purchase agreement, payment maximum	$ 1,300