Derivative Instruments and Hedging Activities (Statement of Gains and Losses on Derivative Instruments Reported in Statement of Comprehensive Income) (Details) - Total derivatives not designated as accounting hedges - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	$ 0	$ 20	$ (3)	$ 27
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	3	11	12	18
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	1	9	1	11
Other credit derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	0	0	(5)	(2)
Equity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	(4)	0	(11)	0
Gain on mortgage and automotive loans, net | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	4	7	13	8
Other income, net of losses | Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	(1)	4	(1)	10
Other income, net of losses | Other credit derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	0	0	(5)	(2)
Other income, net of losses | Equity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	(4)	0	(11)	0
Other operating expenses | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total gain (loss) recognized in earnings	$ 1	$ 9	$ 1	$ 11