COMMISSIONS AND FEES; ADMINISTRATION AND OTHER FIDUCIARY FEES - Commissions and Fees Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Commissions and fees
Commissions and fees	$ 2,803	$ 3,241	$ 8,944	$ 9,552
Investment banking
Commissions and fees
Commissions and fees	856	961	2,695	2,840
Brokerage commissions
Commissions and fees
Commissions and fees	652	682	2,164	2,049
Interchange fees
Commissions and fees
Commissions and fees	2,332	2,178	6,778	6,299
Card-related loan fees
Commissions and fees
Commissions and fees	188	198	533	606
Card rewards and partner payments
Commissions and fees
Commissions and fees	(2,255)	(1,935)	(6,456)	(5,717)
Deposit-related fees
Commissions and fees
Commissions and fees	399	441	1,215	1,262
Transactional service fees
Commissions and fees
Commissions and fees	194	217	611	674
Corporate finance
Commissions and fees
Commissions and fees	146	185	510	620
Insurance distribution revenue
Commissions and fees
Commissions and fees	143	164	448	493
Insurance premiums
Commissions and fees
Commissions and fees	29	31	92	93
Loan servicing
Commissions and fees
Commissions and fees	77	88	238	277
Other
Commissions and fees
Commissions and fees	42	31	116	56
Overdraft fees
Commissions and fees
Commissions and fees	33	35	95	101
Commissions and fees
Commissions and fees
Revenue not accounted for under ASC 606, Revenue from Contracts with Customers	(1,774)	(1,398)	(4,967)	(4,023)
ICG
Commissions and fees
Commissions and fees	2,078	2,232	6,592	6,650
ICG | Investment banking
Commissions and fees
Commissions and fees	856	961	2,695	2,840
ICG | Brokerage commissions
Commissions and fees
Commissions and fees	453	459	1,510	1,431
ICG | Interchange fees
Commissions and fees
Commissions and fees	268	242	804	705
ICG | Card-related loan fees
Commissions and fees
Commissions and fees	16	13	47	39
ICG | Card rewards and partner payments
Commissions and fees
Commissions and fees	(125)	(105)	(375)	(316)
ICG | Deposit-related fees
Commissions and fees
Commissions and fees	239	249	711	696
ICG | Transactional service fees
Commissions and fees
Commissions and fees	171	185	543	556
ICG | Corporate finance
Commissions and fees
Commissions and fees	145	183	506	616
ICG | Insurance distribution revenue
Commissions and fees
Commissions and fees	3	5	13	10
ICG | Insurance premiums
Commissions and fees
Commissions and fees	0	0	0	0
ICG | Loan servicing
Commissions and fees
Commissions and fees	42	38	118	109
ICG | Other
Commissions and fees
Commissions and fees	10	2	20	(36)
GCB
Commissions and fees
Commissions and fees	718	919	2,296	2,593
GCB | Investment banking
Commissions and fees
Commissions and fees	0	0	0	0
GCB | Brokerage commissions
Commissions and fees
Commissions and fees	199	222	654	615
GCB | Interchange fees
Commissions and fees
Commissions and fees	2,063	1,912	5,963	5,507
GCB | Card-related loan fees
Commissions and fees
Commissions and fees	172	172	474	526
GCB | Card rewards and partner payments
Commissions and fees
Commissions and fees	(2,130)	(1,822)	(6,070)	(5,352)
GCB | Deposit-related fees
Commissions and fees
Commissions and fees	160	188	503	554
GCB | Transactional service fees
Commissions and fees
Commissions and fees	22	21	64	74
GCB | Corporate finance
Commissions and fees
Commissions and fees	1	2	4	4
GCB | Insurance distribution revenue
Commissions and fees
Commissions and fees	144	142	429	425
GCB | Insurance premiums
Commissions and fees
Commissions and fees	31	32	96	97
GCB | Loan servicing
Commissions and fees
Commissions and fees	27	25	89	79
GCB | Other
Commissions and fees
Commissions and fees	29	25	90	64
Corporate/Other
Commissions and fees
Commissions and fees	7	90	56	309
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	3
Corporate/Other | Interchange fees
Commissions and fees
Commissions and fees	1	24	11	87
Corporate/Other | Card-related loan fees
Commissions and fees
Commissions and fees	0	13	12	41
Corporate/Other | Card rewards and partner payments
Commissions and fees
Commissions and fees	0	(8)	(11)	(49)
Corporate/Other | Deposit-related fees
Commissions and fees
Commissions and fees	0	4	1	12
Corporate/Other | Transactional service fees
Commissions and fees
Commissions and fees	1	11	4	44
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	(4)	17	6	58
Corporate/Other | Insurance premiums
Commissions and fees
Commissions and fees	(2)	(1)	(4)	(4)
Corporate/Other | Loan servicing
Commissions and fees
Commissions and fees	8	25	31	89
Corporate/Other | Other
Commissions and fees
Commissions and fees	$ 3	$ 4	$ 6	$ 28