Investment Securities - Contractual Maturities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Total Estimated Fair Value
Due in 1 year or less	$ 826
Due after 1 year through 5 years	127
Due after 5 years through 10 years	7
Due after 10 years	37
Total	997	$ 1,192
Total Cost
Due in 1 year or less	825
Due after 1 year through 5 years	126
Due after 5 years through 10 years	7
Due after 10 years	45
Total	$ 1,002
Weighted average yields
Weighted average yields, due within 1 year	5.31%
Weighted average yields, due after 1 years but within 5 years	4.17%
Weighted average yields, due after 5 years but within 10 years	3.48%
Weighted average yield, due after 10 years	2.69%
Total	5.04%
U.S. statutory federal income tax rate	21.00%	21.00%	21.00%
State and municipal obligations
Total Estimated Fair Value
Due in 1 year or less	$ 0
Due after 1 year through 5 years	21
Due after 5 years through 10 years	1
Due after 10 years	26
Total	48	$ 49
Total Cost
Total	54	57
U.S. Government agency obligations
Total Estimated Fair Value
Due in 1 year or less	0
Due after 1 year through 5 years	0
Due after 5 years through 10 years	0
Due after 10 years	3
Total	3	4
Total Cost
Total	3	4
U.S. Government treasury obligations
Total Estimated Fair Value
Due in 1 year or less	80
Due after 1 year through 5 years	59
Due after 5 years through 10 years	0
Due after 10 years	0
Total	138	287
Total Cost
Total	138	289
Mortgage-backed securities
Total Estimated Fair Value
Due in 1 year or less	0
Due after 1 year through 5 years	0
Due after 5 years through 10 years	0
Due after 10 years	9
Total	9	10
Total Cost
Total	10	11
Foreign government bonds and obligations
Total Estimated Fair Value
Due in 1 year or less	714
Due after 1 year through 5 years	3
Due after 5 years through 10 years	0
Due after 10 years	0
Total	717	765
Total Cost
Total	717	765
Other
Total Estimated Fair Value
Due in 1 year or less	32
Due after 1 year through 5 years	44
Due after 5 years through 10 years	5
Due after 10 years	0
Total	81	77
Total Cost
Total	$ 81	$ 77