Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Total revenue	$ 1,643	$ 1,089	$ 3,226	$ 3,375
Revenue, Product and Service [Extensible List]	Product Revenue [Member]	Product Revenue [Member]	Product Revenue [Member]	Product Revenue [Member]
Operating costs and expenses:
Cost of goods sold	$ 148	$ 110	$ 335	$ 280
Research and development	66,170	73,320	124,226	136,930
Selling, general and administrative	43,346	38,224	83,193	108,355
Restructuring		28,402		28,402
Total operating costs and expenses	109,664	140,056	207,754	273,967
Loss from operations	(108,021)	(138,967)	(204,528)	(270,592)
Interest income, net	732	2,686	1,440	7,416
Other income (expense), net	44	(66)	79	89
Net loss	$ (107,245)	$ (136,347)	$ (203,009)	$ (263,087)
Net loss per share—basic and diluted	$ (1.83)	$ (2.63)	$ (3.47)	$ (5.07)
Weighted average number of common shares outstanding—basic and diluted	58,582,569	51,926,074	58,478,970	51,917,417
Comprehensive loss:
Net loss	$ (107,245)	$ (136,347)	$ (203,009)	$ (263,087)
Other comprehensive items:
Unrealized gain (loss) on marketable securities	(49)	2,501	(700)	414
Total other comprehensive gain (loss)	(49)	2,501	(700)	414
Total comprehensive loss	$ (107,294)	$ (133,846)	$ (203,709)	$ (262,673)