COMMISSIONS AND FEES; ADMINISTRATION AND OTHER FIDUCIARY FEES - Commissions and Fees Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Commissions and fees
Total commissions and fees	$ 3,030	$ 3,055
Revenue not accounted for under ASC 606, Revenue from Contracts with Customers	(153)	(143)
Investment banking
Commissions and fees
Total commissions and fees	822	904
Brokerage commissions
Commissions and fees
Total commissions and fees	814	676
Interchange fees
Commissions and fees
Total commissions and fees	2,140	1,965
Card-related loan fees
Commissions and fees
Total commissions and fees	175	195
Card rewards and partner payments
Commissions and fees
Total commissions and fees	(2,003)	(1,815)
Deposit-related fees
Commissions and fees
Total commissions and fees	420	397
Transactional service fees
Commissions and fees
Total commissions and fees	213	225
Corporate finance
Commissions and fees
Total commissions and fees	143	185
Insurance distribution revenue
Commissions and fees
Total commissions and fees	153	171
Insurance premiums
Commissions and fees
Total commissions and fees	32	32
Loan servicing
Commissions and fees
Total commissions and fees	72	92
Other
Commissions and fees
Total commissions and fees	49	28
Overdraft fees
Commissions and fees
Total commissions and fees	32	33
Commissions and fees
Commissions and fees
Revenue not accounted for under ASC 606, Revenue from Contracts with Customers	(1,545)	(1,278)
Institutional Clients Group
Commissions and fees
Total commissions and fees	2,164	2,100
Institutional Clients Group | Investment banking
Commissions and fees
Total commissions and fees	822	904
Institutional Clients Group | Brokerage commissions
Commissions and fees
Total commissions and fees	566	482
Institutional Clients Group | Interchange fees
Commissions and fees
Total commissions and fees	260	222
Institutional Clients Group | Card-related loan fees
Commissions and fees
Total commissions and fees	14	12
Institutional Clients Group | Card rewards and partner payments
Commissions and fees
Total commissions and fees	(124)	(103)
Institutional Clients Group | Deposit-related fees
Commissions and fees
Total commissions and fees	236	208
Institutional Clients Group | Transactional service fees
Commissions and fees
Total commissions and fees	190	174
Institutional Clients Group | Corporate finance
Commissions and fees
Total commissions and fees	142	184
Institutional Clients Group | Insurance distribution revenue
Commissions and fees
Total commissions and fees	5	2
Institutional Clients Group | Insurance premiums
Commissions and fees
Total commissions and fees	0	0
Institutional Clients Group | Loan servicing
Commissions and fees
Total commissions and fees	38	35
Institutional Clients Group | Other
Commissions and fees
Total commissions and fees	15	(20)
Global Consumer Banking
Commissions and fees
Total commissions and fees	839	819
Global Consumer Banking | Investment banking
Commissions and fees
Total commissions and fees	0	0
Global Consumer Banking | Brokerage commissions
Commissions and fees
Total commissions and fees	248	193
Global Consumer Banking | Interchange fees
Commissions and fees
Total commissions and fees	1,875	1,703
Global Consumer Banking | Card-related loan fees
Commissions and fees
Total commissions and fees	155	167
Global Consumer Banking | Card rewards and partner payments
Commissions and fees
Total commissions and fees	(1,874)	(1,685)
Global Consumer Banking | Deposit-related fees
Commissions and fees
Total commissions and fees	183	185
Global Consumer Banking | Transactional service fees
Commissions and fees
Total commissions and fees	21	27
Global Consumer Banking | Corporate finance
Commissions and fees
Total commissions and fees	1	1
Global Consumer Banking | Insurance distribution revenue
Commissions and fees
Total commissions and fees	143	144
Global Consumer Banking | Insurance premiums
Commissions and fees
Total commissions and fees	33	33
Global Consumer Banking | Loan servicing
Commissions and fees
Total commissions and fees	22	26
Global Consumer Banking | Other
Commissions and fees
Total commissions and fees	32	25
Corporate/Other
Commissions and fees
Total commissions and fees	27	136
Corporate/Other | Investment banking
Commissions and fees
Total commissions and fees	0	0
Corporate/Other | Brokerage commissions
Commissions and fees
Total commissions and fees	0	1
Corporate/Other | Interchange fees
Commissions and fees
Total commissions and fees	5	40
Corporate/Other | Card-related loan fees
Commissions and fees
Total commissions and fees	6	16
Corporate/Other | Card rewards and partner payments
Commissions and fees
Total commissions and fees	(5)	(27)
Corporate/Other | Deposit-related fees
Commissions and fees
Total commissions and fees	1	4
Corporate/Other | Transactional service fees
Commissions and fees
Total commissions and fees	2	24
Corporate/Other | Corporate finance
Commissions and fees
Total commissions and fees	0	0
Corporate/Other | Insurance distribution revenue
Commissions and fees
Total commissions and fees	5	25
Corporate/Other | Insurance premiums
Commissions and fees
Total commissions and fees	(1)	(1)
Corporate/Other | Loan servicing
Commissions and fees
Total commissions and fees	12	31
Corporate/Other | Other
Commissions and fees
Total commissions and fees	$ 2	$ 23