Segment Reporting - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Segment revenue	$ 240	$ 2,380	$ 4,486	$ 61,831
Less: Segment expenses
Cost of revenue	(11)	50	0	161
Research and development
Selling, general and administrative	22,231	25,744	68,458	92,330
Restructuring, long-lived assets impairment and related charges, net	0	12,712	(182)	38,939
Net loss	(163,141)	(213,717)	(395,064)	(417,371)
Reportable Segment
Segment Reporting Information [Line Items]
Segment revenue	240	2,380	4,486	61,831
Less: Segment expenses
Cost of revenue	(11)	50	0	161
Research and development
Clinical costs	21,017	12,866	61,984	36,791
Contract manufacturing	9,644	10,504	33,043	30,697
Personnel	27,677	35,885	94,560	125,745
Licenses, collaborations and contingent consideration	76,414	112,532	124,306	123,410
Other R&D	16,711	23,391	53,724	83,773
Selling, general and administrative	22,231	25,744	68,458	92,330
Restructuring, long-lived assets impairment and related charges, net	0	12,712	(182)	38,939
Plus: Other segment items	10,302	17,587	36,343	52,644
Net loss	$ (163,141)	$ (213,717)	$ (395,064)	$ (417,371)