Segment - Schedule of Reporting Segment (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenue	[1]	$ 61	$ 130	$ 84,683
Total research and development expenses		171,603	182,945	159,188
General and administrative		52,041	66,983	117,307
Other operating income, net		(3,309)	(2,790)	(4,754)
Acquired in-process research and development		87,184	0	0
Impairment of long-lived assets		51,297	0	0
Total operating expenses		358,816	247,138	271,741
Loss from operations		(358,755)	(247,008)	(187,058)
Interest income, net		24,068	23,453	7,053
Other income, net		4,694	1,846	1,887
Impairment of other investments		(13,001)	(12,923)	(5,000)
Total other income, net		15,761	12,376	3,940
Net loss		(342,994)	(234,632)	(183,118)
Reportable segment
Segment Reporting Information [Line Items]
Revenue		61	130	84,683
Technical operations		63,419	64,393	55,412
Clinical operations		39,783	31,802	19,191
Research activities		37,772	53,567	57,328
Facilities and technology		26,342	25,636	25,081
Operations management		4,287	7,547	2,176
Total research and development expenses		171,603	182,945	159,188
Business support		33,973	47,428	84,500
Corporate expenses and outside services		14,450	15,575	27,717
Facilities and technology		3,618	3,980	5,090
General and administrative		52,041	66,983	117,307
Other operating income, net		(3,309)	(2,790)	(4,754)
Acquired in-process research and development		87,184	0	0
Impairment of long-lived assets		51,297	0	0
Total operating expenses		358,816	247,138	271,741
Loss from operations		(358,755)	(247,008)	(187,058)
Interest income, net		24,068	23,453	7,053
Other income, net		4,694	1,846	1,887
Impairment of other investments		(13,001)	(12,923)	(5,000)
Total other income, net		15,761	12,376	3,940
Net loss		$ (342,994)	$ (234,632)	$ (183,118)

[1] Includes related-party revenue of zero for both the years ended December 31, 2024 and 2023 and $84,653 for the year ended December 31, 2022.