Income Taxes - Schedule of Effective Tax Rate of Provision for Income Taxes Differs from Federal Statutory Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amount
Federal statutory income taxes	$ (74)	$ (59)	$ (63)
State taxes, net of federal benefit	0	0	2
Domestic research and development credits	(15)	(12)	(14)
Equity investment	(12)	(12)	(1)
Stock based compensation	4	5	6
Other items	5	2	0
Change in valuation allowance	92	77	76
Provision for income taxes	$ 0	$ 1	$ 6
Percent
Federal statutory income taxes	21.00%	21.00%	21.00%
State taxes, net of federal benefit	0.10%	(0.10%)	(0.80%)
Domestic research and development credits	4.20%	4.40%	4.60%
Equity investment	3.40%	4.10%	0.40%
Stock based compensation	(1.10%)	(1.90%)	(2.10%)
Other items	(1.40%)	(0.50%)	0.00%
Change in valuation allowance	(26.10%)	(27.20%)	(25.10%)
Provision for income taxes	0.10%	(0.20%)	(2.00%)