Derivative Financial Instruments - Amounts Related to Derivative Instruments Not Designated as Hedges (Details) - Not designated as hedges - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	$ 96	$ (15)	$ 159	$ (56)
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	16	10	26	25
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	(1)	6	1	13
Mortgage banking | Interest rate contracts | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	(2)	(8)	(5)	(4)
MSRs | Interest rate contracts | Mortgage banking income
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax Gain (Loss) Recognized in Income	$ 83	$ (23)	$ 137	$ (90)