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
	Mar. 31, 2026	Mar. 31, 2025
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	$ 143	$ (42)
Mortgage Banking \| Interest rate contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	(18)	85
Customer Contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	85	47
Customer Contracts \| Interest rate contracts
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	29	(21)
Customer Contracts \| Foreign exchange contracts and other
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	56	68
Other Risk Management Activity \| Foreign exchange contracts and other
Derivative [Line Items]
Derivative instruments not designated as hedging instruments gain (loss), net	$ 76	$ (174)