Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total revenue	$ 1,639	$ 3,570	$ 5,014	$ 4,908
Type of Revenue [Extensible List]	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember	us-gaap:CollaborativeArrangementMember
Operating costs and expenses:
Cost of goods sold	$ 149	$ 137	$ 429	$ 181
Research and development	74,078	102,108	211,008	277,565
Selling, general and administrative	35,099	88,502	143,454	260,648
Restructuring	(529)		27,873
Total operating costs and expenses	108,797	190,747	382,764	538,394
Loss from operations	(107,158)	(187,177)	(377,750)	(533,486)
Interest income, net	1,347	7,227	8,763	21,889
Other income (expense), net	76	(8)	165	12
Net loss	$ (105,735)	$ (179,958)	$ (368,822)	$ (511,585)
Net loss per share—basic and diluted	$ (2.03)	$ (3.48)	$ (7.10)	$ (10.13)
Weighted average number of common shares outstanding—basic and diluted	51,981,468	51,704,687	51,938,923	50,496,489
Comprehensive loss:
Net loss	$ (105,735)	$ (179,958)	$ (368,822)	$ (511,585)
Other comprehensive items:
Unrealized gain (loss) on marketable securities	(763)	202	(349)	2,292
Total other comprehensive gain (loss)	(763)	202	(349)	2,292
Total comprehensive loss	(106,498)	(179,756)	(369,171)	(509,293)
Product Revenue [Member]
Total revenue	$ 1,639	1,478	$ 5,014	1,997
Collaboration Revenue [Member]
Total revenue		$ 2,092		$ 2,911