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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ 34	$ 17	$ 82	$ 43
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	4	15	13	28
Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	9	11	29	32
Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	5	2	13	5
Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(4)	(13)	(26)	(27)
Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	20	2	53	5
Corporate services income
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	23	24	59	64
Corporate services income | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	5	16	23	31
Corporate services income | Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	9	11	29	32
Corporate services income | Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	5	2	13	5
Corporate services income | Credit
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	4	(5)	(6)	(4)
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)	28	5	36	5
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)	28	5	36	5
Other income
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(17)	(12)	(13)	(26)
Other income | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	(1)	(1)	(10)	(3)
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)	(8)	(8)	(20)	(23)
Other income | Other
Derivative Instruments, Gain (Loss) [Line Items]
Total net gains (losses)	$ (8)	$ (3)	$ 17	$ 0