Property and Equipment - Summary of Property and Equipment, Net (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 90	$ 88
Less: Accumulated depreciation and amortization	(50)	(41)
Property and equipment, net	$ 40	47
Minimum
Property, Plant and Equipment [Line Items]
Useful Life (in years)	3 years
Maximum
Property, Plant and Equipment [Line Items]
Useful Life (in years)	10 years
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 57	56
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful Life (in years)	6 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful Life (in years)	10 years
Scientific equipment
Property, Plant and Equipment [Line Items]
Useful Life (in years)	5 years
Property and equipment, gross	$ 28	27
Furniture and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4	4
Furniture and equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful Life (in years)	3 years
Furniture and equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful Life (in years)	5 years
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1	$ 1