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, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net gains/(losses), loans and leases	$ (18)	$ (15)	$ (65)	$ (29)
Net gains/(losses), other assets	0	(1)	0	(5)
Gains (losses) on financial assets measured on non-recurring basis	(19)	(17)	(66)	(36)
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)	$ (1)	$ (1)	$ (2)