Revenues - Summary of Revenues by Collaboration, Category of Revenue and Method of Recognition (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Total revenues	$ 247	$ 258	$ 117
Total revenues from collaborations	214	207	80
Total revenues from a customer	33	51	37
License and development services
Disaggregation of Revenue [Line Items]
Total revenues	221	222	80
License and development services | Over time | Gilead Collaboration
Disaggregation of Revenue [Line Items]
Total revenues	214	207	75
R&D services | Over time | Gilead Collaboration
Disaggregation of Revenue [Line Items]
Total revenues	10	8	4
Access rights | Over time | Gilead Collaboration
Disaggregation of Revenue [Line Items]
Total revenues	16	28	33
License | Point in time | Taiho Collaboration
Disaggregation of Revenue [Line Items]
Total revenues	7	15	0
Other | Over time | Taiho Collaboration
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 5