Derivatives - Net Gains (Losses) Relating to Free-Standing Derivative Instruments Used For Customer Accommodation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Interest Rate Contract | Customer Contracts | Corporate banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 12	$ 9	$ 18	$ 16
Interest Rate Contract | Customer Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(6)	0	(13)	0
Interest Rate Contract | Interest Rate Lock Commitments | Mortgage banking net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	34	22	58	35
Commodity Contract | Customer Contracts | Corporate banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	2	2	3	4
Commodity Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	0	(1)	0	(1)
Foreign Exchange Contract | Customer Contracts | Corporate banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	12	13	24	27
Foreign Exchange Contract | Customer Contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	4	7	8	5
Foreign Exchange Contract | Fair Value Adjustments on Hedges and Derivative Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 0	$ 0	$ 0	$ 1