Derivatives and Hedging Activities - Pre-Tax Net Gains (Losses) on Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ 16	$ 34	$ 35	$ 82
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	8	4	20	13
Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	12	9	34	29
Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	4	5	12	13
Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(8)	(4)	(22)	(26)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	20	(9)	53
Corporate services income
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	25	23	70	59
Corporate services income | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	8	5	19	23
Corporate services income | Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	12	9	34	29
Corporate services income | Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	4	5	12	13
Corporate services income | Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	1	4	5	(6)
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)	0	28	13	36
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)	0	28	13	36
Other income
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(9)	(17)	(48)	(13)
Other income | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	0	(1)	1	(10)
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)	(8)	(27)	(20)
Other income | Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ 0	$ (8)	$ (22)	$ 17