Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Collaboration revenue	$ 11,992	$ 13,266	$ 38,192	$ 38,548
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 113,696	$ 96,651	$ 326,088	$ 319,945
General and administrative	29,403	22,145	87,503	66,680
Total operating expenses	143,099	118,796	413,591	386,625
Operating loss	(131,107)	(105,530)	(375,399)	(348,077)
Other income (expense), net:
Interest income	12,740	1,945	37,373	3,188
Loss from equity method investment	(3,857)	(1,834)	(10,905)	(7,831)
Change in fair value of contingent consideration	0	(7,810)	(100)	(8,059)
Total other income (expense), net	8,883	(7,699)	26,368	(12,702)
Net loss	$ (122,224)	$ (113,229)	$ (349,031)	$ (360,779)
Net loss per share, basic	$ (1.38)	$ (1.49)	$ (3.96)	$ (4.78)
Net loss per share, diluted	$ (1.38)	$ (1.49)	$ (3.96)	$ (4.78)
Weighted average shares outstanding, basic	88,645	76,047	88,204	75,543
Weighted average shares outstanding, diluted	88,645	76,047	88,204	75,543
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	$ 142	$ 991	$ 1,649	$ (5,069)
Other comprehensive gain (loss) from equity method investment	154	(805)	2,240	(1,667)
Comprehensive loss	$ (121,928)	$ (113,043)	$ (345,142)	$ (367,515)