Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Revenue	$ 34	$ 25	$ 50	$ 117
Operating expenses:
Research and development	39,500	43,849	122,935	135,950
General and administrative	11,769	15,507	37,519	53,816
Other operating income, net	(730)	(292)	(2,796)	(2,149)
Total operating expenses	50,539	59,064	157,658	187,617
Loss from operations	(50,505)	(59,039)	(157,608)	(187,500)
Interest income, net	5,965	6,608	19,148	16,369
Other (expense) income, net	(43)	1,578	402	2,352
Impairment of other investments	0	0	(13,001)	(12,923)
Total other income, net	5,922	8,186	6,549	5,798
Net loss	(44,583)	(50,853)	(151,059)	(181,702)
Other comprehensive loss:
Net unrealized gain on marketable securities	1,157	1,198	854	6,418
Comprehensive loss	$ (43,426)	$ (49,655)	$ (150,205)	$ (175,284)
Net loss per common share, basic (in dollars per share)	$ (0.17)	$ (0.20)	$ (0.59)	$ (0.73)
Net loss per common share, diluted (in dollars per share)	$ (0.17)	$ (0.20)	$ (0.59)	$ (0.73)
Weighted-average shares used to compute net loss per common share, basic (in shares)	256,309	251,318	255,323	250,377
Weighted-average shares used to compute net loss per common share, diluted (in shares)	256,309	251,318	255,323	250,377