Investment Securities - Summary (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Available-for-sale debt securities:
Cost	$ 1,002
Estimated Fair Value	997	$ 1,192
Equity securities
Cost	54	53
Gross Unrealized Gains	0	4
Gross Unrealized Losses	(8)	(9)
Estimated Fair Value	46	48
Total Cost	1,056	1,256
Total Gross Unrealized Gains	2	5
Total Gross Unrealized Losses	(16)	(21)
Total Estimated Fair Value	1,043	1,240
State and municipal obligations
Available-for-sale debt securities:
Cost	54	57
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(7)	(9)
Estimated Fair Value	48	49
U.S. Government agency obligations
Available-for-sale debt securities:
Cost	3	4
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	3	4
U.S. Government treasury obligations
Available-for-sale debt securities:
Cost	138	289
Gross Unrealized Gains	1	0
Gross Unrealized Losses	0	(2)
Estimated Fair Value	138	287
Mortgage-backed securities
Available-for-sale debt securities:
Cost	10	11
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Estimated Fair Value	9	10
Foreign government bonds and obligations
Available-for-sale debt securities:
Cost	717	765
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	717	765
Other
Available-for-sale debt securities:
Cost	81	77
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 81	$ 77