Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Abstract]
Total revenue	$ 1,440	$ 1,639	$ 4,666	$ 5,014
Operating costs and expenses:
Cost of goods sold	131	149	466	429
Research and development	83,497	74,078	207,723	211,008
Selling, general and administrative	48,706	35,099	131,899	143,454
Restructuring		(529)		27,873
Total operating costs and expenses	132,334	108,797	340,088	382,764
Loss from operations	(130,894)	(107,158)	(335,422)	(377,750)
Interest income, net	692	1,347	2,132	8,763
Other income, net	31	76	110	165
Net loss	$ (130,171)	$ (105,735)	$ (333,180)	$ (368,822)
Net loss per share—basic and diluted	$ (2.21)	$ (2.03)	$ (5.69)	$ (7.10)
Weighted average number of common shares outstanding—basic and diluted	58,819,548	51,981,468	58,593,743	51,938,923
Comprehensive loss:
Net loss	$ (130,171)	$ (105,735)	$ (333,180)	$ (368,822)
Other comprehensive items:
Unrealized loss on marketable securities	(21)	(763)	(721)	(349)
Total other comprehensive loss	(21)	(763)	(721)	(349)
Total comprehensive loss	$ (130,192)	$ (106,498)	$ (333,901)	$ (369,171)