COMMISSIONS AND FEES; ADMINISTRATION AND OTHER FIDUCIARY FEES - Commissions and Fees Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Commissions and fees
Commissions and fees	$ 3,111	$ 3,256	$ 6,141	$ 6,311
Investment banking
Commissions and fees
Commissions and fees	1,012	967	1,839	1,879
Brokerage commissions
Commissions and fees
Commissions and fees	697	690	1,512	1,367
Interchange fees
Commissions and fees
Commissions and fees	2,306	2,156	4,446	4,121
Card-related loan fees
Commissions and fees
Commissions and fees	170	213	345	408
Card rewards and partner payments
Commissions and fees
Commissions and fees	(2,197)	(1,967)	(4,201)	(3,782)
Deposit-related fees
Commissions and fees
Commissions and fees	397	424	816	821
Transactional service fees
Commissions and fees
Commissions and fees	204	232	417	457
Corporate finance
Commissions and fees
Commissions and fees	220	250	364	435
Insurance distribution revenue
Commissions and fees
Commissions and fees	152	157	305	329
Insurance premiums
Commissions and fees
Commissions and fees	31	31	63	62
Loan servicing
Commissions and fees
Commissions and fees	89	96	161	189
Other
Commissions and fees
Commissions and fees	30	7	74	25
Commissions and fees
Commissions and fees
Revenue not accounted for under ASC 606, Revenue from Contracts with Customers	(1,648)	(1,347)	(3,193)	(2,625)
Overdraft fees
Commissions and fees
Commissions and fees	30	33	62	66
ICG
Commissions and fees
Commissions and fees	2,345	2,310	4,514	4,418
ICG | Investment banking
Commissions and fees
Commissions and fees	1,012	967	1,839	1,879
ICG | Brokerage commissions
Commissions and fees
Commissions and fees	491	490	1,057	972
ICG | Interchange fees
Commissions and fees
Commissions and fees	276	241	536	463
ICG | Card-related loan fees
Commissions and fees
Commissions and fees	17	14	31	26
ICG | Card rewards and partner payments
Commissions and fees
Commissions and fees	(126)	(109)	(250)	(211)
ICG | Deposit-related fees
Commissions and fees
Commissions and fees	236	239	472	447
ICG | Transactional service fees
Commissions and fees
Commissions and fees	182	197	372	371
ICG | Corporate finance
Commissions and fees
Commissions and fees	219	249	361	433
ICG | Insurance distribution revenue
Commissions and fees
Commissions and fees	5	2	10	5
ICG | Insurance premiums
Commissions and fees
Commissions and fees	0	0	0	0
ICG | Loan servicing
Commissions and fees
Commissions and fees	38	36	76	71
ICG | Other
Commissions and fees
Commissions and fees	(5)	(16)	10	(38)
GCB
Commissions and fees
Commissions and fees	743	860	1,578	1,674
GCB | Investment banking
Commissions and fees
Commissions and fees	0	0	0	0
GCB | Brokerage commissions
Commissions and fees
Commissions and fees	206	199	455	393
GCB | Interchange fees
Commissions and fees
Commissions and fees	2,025	1,892	3,900	3,595
GCB | Card-related loan fees
Commissions and fees
Commissions and fees	147	187	302	354
GCB | Card rewards and partner payments
Commissions and fees
Commissions and fees	(2,065)	(1,844)	(3,940)	(3,530)
GCB | Deposit-related fees
Commissions and fees
Commissions and fees	160	181	343	366
GCB | Transactional service fees
Commissions and fees
Commissions and fees	21	26	42	53
GCB | Corporate finance
Commissions and fees
Commissions and fees	1	1	3	2
GCB | Insurance distribution revenue
Commissions and fees
Commissions and fees	142	138	285	283
GCB | Insurance premiums
Commissions and fees
Commissions and fees	32	32	65	65
GCB | Loan servicing
Commissions and fees
Commissions and fees	40	28	62	54
GCB | Other
Commissions and fees
Commissions and fees	34	20	61	39
Corporate/Other
Commissions and fees
Commissions and fees	23	86	49	219
Corporate/Other | Investment banking
Commissions and fees
Commissions and fees	0	0	0	0
Corporate/Other | Brokerage commissions
Commissions and fees
Commissions and fees	0	1	0	2
Corporate/Other | Interchange fees
Commissions and fees
Commissions and fees	5	23	10	63
Corporate/Other | Card-related loan fees
Commissions and fees
Commissions and fees	6	12	12	28
Corporate/Other | Card rewards and partner payments
Commissions and fees
Commissions and fees	(6)	(14)	(11)	(41)
Corporate/Other | Deposit-related fees
Commissions and fees
Commissions and fees	1	4	1	8
Corporate/Other | Transactional service fees
Commissions and fees
Commissions and fees	1	9	3	33
Corporate/Other | Corporate finance
Commissions and fees
Commissions and fees	0	0	0	0
Corporate/Other | Insurance distribution revenue
Commissions and fees
Commissions and fees	5	17	10	41
Corporate/Other | Insurance premiums
Commissions and fees
Commissions and fees	(1)	(1)	(2)	(3)
Corporate/Other | Loan servicing
Commissions and fees
Commissions and fees	11	32	23	64
Corporate/Other | Other
Commissions and fees
Commissions and fees	$ 1	$ 3	$ 3	$ 24