Financial Derivatives (Gains (Losses) on Derivatives Not Designated As Hedging Instruments under GAAP) (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Total gains (losses) from derivatives not designated as hedging instruments	$ 176	$ 820	$ 507
Mortgage Banking | Interest Rate Contract
Derivative [Line Items]
Total gains (losses) from derivatives not designated as hedging instruments	(78)	792	405
Customer-related Contracts
Derivative [Line Items]
Total gains (losses) from derivatives not designated as hedging instruments	284	366	239
Customer-related Contracts | Interest Rate Contract
Derivative [Line Items]
Total gains (losses) from derivatives not designated as hedging instruments	149	210	125
Customer-related Contracts | Foreign Exchange And Other Contract
Derivative [Line Items]
Total gains (losses) from derivatives not designated as hedging instruments	135	156	114
Other Risk Management Activity | Foreign Exchange And Other Contract
Derivative [Line Items]
Total gains (losses) from derivatives not designated as hedging instruments	$ (30)	$ (338)	$ (137)