Income Taxes - Schedule of Significant Components of Deferred Tax Assets for Federal and State Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Deferred tax assets:
Federal and state net operating loss carryforwards	$ 39	$ 5
Research and development credits carryforwards	59	42
Stock-based compensation	26	27
Depreciation and amortization	3	3
Deferred revenue	19	45
Lease liability	22	24
Capitalized research and development costs	250	178
Other	7	6
Total deferred tax assets	425	330
Deferred tax liabilities:
Right-of-use assets	(13)	(14)
Total deferred tax liabilities	(13)	(14)
Less valuation allowance	(412)	(316)
Net deferred tax assets (liabilities)	$ 0	$ 0