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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	$ (53)	$ 127	$ (195)	$ 125
Mortgage Banking | Interest Rate Contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	(224)	(245)	(301)	(700)
Customer Contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	42	63	191	253
Customer Contracts | Interest Rate Contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	11	65	46	231
Customer Contracts | Foreign exchange contracts and other
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	31	(2)	145	22
Other Risk Management Activity | Foreign exchange contracts and other
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	$ 129	$ 309	$ (85)	$ 572