Securities - Pre-Tax Net Securities Gains (Losses) by Type (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total net securities gains	$ 0	$ 4	$ 2	$ 4	$ 2
Non-agency RMBS
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total net securities gains	0	49	0	49	2
U.S. Treasury
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total net securities gains	1	11	0	12	(4)
Corporate bonds
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total net securities gains	(4)	(47)	0	(51)	0
State and political subdivisions
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total net securities gains	0	(13)	0	(13)	0
Other
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total net securities gains	$ 3	$ 4	$ 2	$ 7	$ 4