Derivatives - Net Gains (Losses) Relating to Free-Standing Derivative Instruments Used For Customer Accommodation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest Rate Contract | Customer Contracts | Corporate banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	$ 12	$ 7	$ 30	$ 23
Interest Rate Contract | Customer Contracts | Other noninterest expense
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	(5)	0	(18)	0
Interest Rate Contract | Interest Rate Lock Commitments | Mortgage banking net revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	50	17	108	52
Commodity Contract | Customer Contracts | Corporate banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	3	3	6	7
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	0	0	(1)
Foreign Exchange Contract | Customer Contracts | Corporate banking revenue
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	12	16	36	43
Foreign Exchange Contract | Customer Contracts | Other noninterest income
Derivative Instruments, Gain (Loss) [Line Items]
Net gains (losses) recorded in earnings	7	3	15	8
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