Derivative Financial Instruments - Amounts Related to Derivative Instruments Not Designated as Hedges (Details) - Not designated as hedges - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	$ (9)	$ 39	$ 102
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	40	50	52
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	21	1	11
Mortgage banking | Interest rate contracts | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	(5)	(12)	8
MSRs | Interest rate contracts | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	$ (65)	$ 0	$ 31