CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Total revenues	$ 69,856	$ 132,299	$ 82,271
Operating expenses:
Research and development	151,117	114,592	114,522
General and administrative	43,812	38,600	38,489
Restructuring charge		1,487	21,433
Total operating expenses	194,929	154,679	174,444
Loss from operations	(125,073)	(22,380)	(92,173)
Investment income, net	51	729	4,424
Non-cash interest expense on liability related to the sale of future royalties and convertible senior notes	(13,103)	(23,107)	(16,879)
Interest expense on convertible senior notes	(47)	(95)	(95)
Other (expense) income, net	(1,131)	481	590
Net loss	(139,303)	(44,372)	(104,133)
Total comprehensive loss	$ (139,303)	$ (44,372)	$ (104,133)
Basic net (loss) income per common share	$ (0.68)	$ (0.25)	$ (0.70)
Diluted net (loss) income per common share	$ (0.68)	$ (0.25)	$ (0.70)
Basic weighted average common shares outstanding (in shares)	206,147	176,153	148,311
Diluted weighted average common shares outstanding (in shares)	206,147	176,153	148,311
Non-cash royalty revenue related to the sale of future royalties
Revenues:
Total revenues	$ 46,808	$ 68,529	$ 47,415
License and milestone fees
Revenues:
Total revenues	22,650	63,742	34,788
Research and development support
Revenues:
Total revenues	$ 398	$ 28	$ 68