COMMISSIONS AND FEES; ADMINISTRATION AND OTHER FIDUCIARY FEES - Commissions and Fees Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Commissions and fees
Commissions and fees	$ 2,926	$ 3,030
Investment banking
Commissions and fees
Commissions and fees	914	827
Brokerage commissions
Commissions and fees
Commissions and fees	657	814
Interchange fees
Commissions and fees
Commissions and fees	2,262	2,139
Card-related loan fees
Commissions and fees
Commissions and fees	173	175
Card rewards and partner payments
Commissions and fees
Commissions and fees	(2,214)	(2,003)
Deposit-related fees
Commissions and fees
Commissions and fees	384	420
Transactional service fees
Commissions and fees
Commissions and fees	230	213
Corporate finance
Commissions and fees
Commissions and fees	179	143
Insurance distribution revenue
Commissions and fees
Commissions and fees	136	153
Insurance premiums
Commissions and fees
Commissions and fees	28	32
Loan servicing
Commissions and fees
Commissions and fees	78	72
Other
Commissions and fees
Commissions and fees	99	45
Overdraft fees
Commissions and fees
Commissions and fees	31	32
Commissions and fees
Commissions and fees
Revenue not accounted for under ASC 606, Revenue from Contracts with Customers	(1,721)	(1,545)
ICG
Commissions and fees
Commissions and fees	2,200	2,164
ICG | Investment banking
Commissions and fees
Commissions and fees	910	822
ICG | Brokerage commissions
Commissions and fees
Commissions and fees	471	566
ICG | Interchange fees
Commissions and fees
Commissions and fees	278	260
ICG | Card-related loan fees
Commissions and fees
Commissions and fees	13	14
ICG | Card rewards and partner payments
Commissions and fees
Commissions and fees	(153)	(124)
ICG | Deposit-related fees
Commissions and fees
Commissions and fees	245	236
ICG | Transactional service fees
Commissions and fees
Commissions and fees	195	190
ICG | Corporate finance
Commissions and fees
Commissions and fees	178	142
ICG | Insurance distribution revenue
Commissions and fees
Commissions and fees	4	5
ICG | Insurance premiums
Commissions and fees
Commissions and fees	0	0
ICG | Loan servicing
Commissions and fees
Commissions and fees	42	38
ICG | Other
Commissions and fees
Commissions and fees	17	15
GCB
Commissions and fees
Commissions and fees	720	839
GCB | Investment banking
Commissions and fees
Commissions and fees	4	5
GCB | Brokerage commissions
Commissions and fees
Commissions and fees	186	248
GCB | Interchange fees
Commissions and fees
Commissions and fees	1,984	1,874
GCB | Card-related loan fees
Commissions and fees
Commissions and fees	160	155
GCB | Card rewards and partner payments
Commissions and fees
Commissions and fees	(2,061)	(1,874)
GCB | Deposit-related fees
Commissions and fees
Commissions and fees	139	183
GCB | Transactional service fees
Commissions and fees
Commissions and fees	35	21
GCB | Corporate finance
Commissions and fees
Commissions and fees	1	1
GCB | Insurance distribution revenue
Commissions and fees
Commissions and fees	132	143
GCB | Insurance premiums
Commissions and fees
Commissions and fees	29	33
GCB | Loan servicing
Commissions and fees
Commissions and fees	30	22
GCB | Other
Commissions and fees
Commissions and fees	81	28
Corporate/Other
Commissions and fees
Commissions and fees	6	27
Corporate/Other | Investment banking
Commissions and fees
Commissions and fees	0	0
Corporate/Other | Brokerage commissions
Commissions and fees
Commissions and fees	0	0
Corporate/Other | Interchange fees
Commissions and fees
Commissions and fees	0	5
Corporate/Other | Card-related loan fees
Commissions and fees
Commissions and fees	0	6
Corporate/Other | Card rewards and partner payments
Commissions and fees
Commissions and fees	0	(5)
Corporate/Other | Deposit-related fees
Commissions and fees
Commissions and fees	0	1
Corporate/Other | Transactional service fees
Commissions and fees
Commissions and fees	0	2
Corporate/Other | Corporate finance
Commissions and fees
Commissions and fees	0	0
Corporate/Other | Insurance distribution revenue
Commissions and fees
Commissions and fees	0	5
Corporate/Other | Insurance premiums
Commissions and fees
Commissions and fees	(1)	(1)
Corporate/Other | Loan servicing
Commissions and fees
Commissions and fees	6	12
Corporate/Other | Other
Commissions and fees
Commissions and fees	$ 1	$ 2