Financial Derivatives (Gains (Losses) on Derivatives Not Designated As Hedging Instruments under GAAP) (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	$ (42)	$ (53)	$ (140)	$ (195)
Mortgage Banking | Interest rate contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	203	(224)	35	(301)
Customer Contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	56	42	94	191
Customer Contracts | Interest rate contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	(21)	11	(58)	46
Customer Contracts | Foreign exchange contracts and other
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	77	31	152	145
Other Risk Management Activity | Foreign exchange contracts and other
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	$ (301)	$ 129	$ (269)	$ (85)