Derivative Financial Instruments - Derivative Instruments Not Designated as a Hedge Effect on the Consolidated Statements of Income (Details) - Hedged Items No Longer Designated - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	$ (41)	$ (26)
Client-related and other risk management | Interest rate contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	15	11
Client-related and other risk management | Foreign exchange contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	7	(2)
Mortgage banking | Interest rate contracts | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	4	(15)
MSRs | Interest rate contracts | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	$ (67)	$ (20)