Derivatives and Hedging Activities - Pre-Tax Net Gains (Losses) on Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ 22	$ 34	$ 19	$ 48
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	5	7	11	9
Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	11	8	23	20
Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	4	6	8	8
Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(10)	(7)	(14)	(22)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	12	20	(9)	33
Corporate services income
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	19	27	46	36
Corporate services income | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	5	7	11	18
Corporate services income | Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	11	8	23	20
Corporate services income | Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	4	6	8	8
Corporate services income | Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(1)	6	4	(10)
Corporate services income | Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer mortgage income
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	12	4	13	8
Consumer mortgage income | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer mortgage income | Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer mortgage income | Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer mortgage income | Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Consumer mortgage income | Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	12	4	13	8
Other income
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(9)	3	(40)	4
Other income | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	(9)
Other income | Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Other income | Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	0	0	0
Other income | Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(9)	(13)	(18)	(12)
Other income | Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ 0	$ 16	$ (22)	$ 25