Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Revenue	[1]	$ 27	$ 35,741	$ 92	$ 36,294
Operating expenses:
Research and development		47,471	43,719	92,101	79,549
General and administrative		19,030	30,454	38,309	64,875
Other operating income, net		(569)	(1,171)	(1,857)	(2,293)
Total operating expenses		65,932	73,002	128,553	142,131
Loss from operations		(65,905)	(37,261)	(128,461)	(105,837)
Interest income, net		5,264	952	9,761	1,349
Other (expense) income, net		(326)	(14)	774	21
Impairment of other investments		(2,923)	0	(12,923)	0
Total other income (loss), net		2,015	938	(2,388)	1,370
Net loss		(63,890)	(36,323)	(130,849)	(104,467)
Comprehensive loss:
Net unrealized gain (loss) on marketable securities		1,500	(1,751)	5,220	(6,728)
Comprehensive loss		$ (62,390)	$ (38,074)	$ (125,629)	$ (111,195)
Net loss per common share, basic (in dollars per share)		$ (0.26)	$ (0.15)	$ (0.52)	$ (0.43)
Net loss per common share, diluted (in dollars per share)		$ (0.26)	$ (0.15)	$ (0.52)	$ (0.43)
Weighted-average shares used to compute net loss per common share, basic (in shares)		250,204	246,312	249,899	245,251
Weighted-average shares used to compute net loss per common share, diluted (in shares)		250,204	246,312	249,899	245,251

[1] (1)    None of the revenue for the three and six months ended June 30, 2023 was from a related-party. Substantially all of the revenue for the three and six months ended June 30, 2022 was from a related-party.