Segments of Business - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting, Asset Reconciling Item [Line Items]
Total revenues	$ 258	$ 117	$ 112
Less:
Impairment of long-lived assets	20	0	0
Interest income, net	4	2	2
Income tax expense	1	6	1
Net loss	(283)	(307)	(267)
Reportable segment
Segment Reporting, Asset Reconciling Item [Line Items]
Total revenues	258	117	112
Less:
Late-stage development programs	252	168	124
Early-stage development and preclinical programs	132	128	145
Compensation and personnel costs	250	223	189
Depreciation and amortization	10	8	6
Impairment of long-lived assets	20	0	0
Interest income, net	(48)	(39)	(13)
Income tax expense	1	6	1
Other segment items	89	92	89
Partnership reimbursements	(165)	(162)	(162)
Net loss	$ (283)	$ (307)	$ (267)