Fair Value of Assets and Liabilities - Gains/(losses) on Nonrecurring Fair Value Measurements (Details) - Non Recurring - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains/(losses),loans and leases	$ (15)	$ (6)	$ (29)	$ (7)
Net gains/(losses), other assets	(1)	(4)	(5)	(8)
Gains (losses) on financial assets measured on non-recurring basis	(17)	(12)	(36)	(19)
SBAs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains/(losses), loans held for sale - SBAs and USDA	$ (1)	$ (2)	$ (2)	$ (4)