Investment Securities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale [Line Items]
Accrued interest available-for-sale debt securities	$ 10	$ 12
Available-for-sale debt securities:
Cost	4,055
Estimated Fair Value	4,016
Equity securities
Cost	65	66
Gross Unrealized Gains	0	17
Gross Unrealized Losses	(16)	(4)
Estimated Fair Value	49	79
Total Cost	4,120	2,548
Total Gross Unrealized Gains	2	48
Total Gross Unrealized Losses	(57)	(5)
Total Estimated Fair Value	4,065	2,591
State and municipal obligations
Available-for-sale debt securities:
Cost	72	106
Gross Unrealized Gains	1	5
Gross Unrealized Losses	(8)	0
Estimated Fair Value	65	111
U.S. Government agency obligations
Available-for-sale debt securities:
Cost	6	6
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	6	6
U.S. Government treasury obligations
Available-for-sale debt securities:
Cost	3,257	1,680
Gross Unrealized Gains	1	25
Gross Unrealized Losses	(31)	(1)
Estimated Fair Value	3,227	1,704
Mortgage-backed securities
Available-for-sale debt securities:
Cost	14	17
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Estimated Fair Value	14	18
Foreign government bonds and obligations
Available-for-sale debt securities:
Cost	673	630
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2)	0
Estimated Fair Value	671	630
Other
Available-for-sale debt securities:
Cost	33	43
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 33	$ 43