Derivative Financial Instruments - Net Gains (Losses) Recorded in the Consolidated Statements of Income Relating to Free-Standing Derivative Instruments Used For Customer Accommodation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 11	$ 117	$ 361	$ 177
Interest rate contracts | Customer contracts | Commercial banking revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	12	12	26	18
Interest rate contracts | Fair value adjustment | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(1)	(6)	(34)	(13)
Interest rate contracts | Interest rate lock commitments | Mortgage banking net revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	82	34	182	58
Commodity contracts | Customer contracts | Commercial banking revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	4	2	7	3
Commodity contracts | Fair value adjustment | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	0	0	(1)	0
Commodity contracts | Credit losses | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(1)	0	(1)	0
Foreign exchange contracts | Other noninterest income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(6)	(3)	8	(5)
Foreign exchange contracts | Customer contracts | Commercial banking revenue
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	14	12	26	24
Foreign exchange contracts | Customer contracts | Other noninterest income
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	(3)	4	3	8
Foreign exchange contracts | Fair value adjustment | Other noninterest expense
Derivative Instruments, Gain (Loss)
Net gains (losses) recorded in earnings	$ 1	$ 0	$ (1)	$ 0