ALLOWANCE FOR CREDIT LOSSES - Allowance for Loan Losses Roll Forward by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Dec. 31, 2015
Allowance for credit losses
Allowance for loan losses at beginning of period	$ 12,304	$ 14,075	$ 12,626	$ 15,994
Charge-offs	(1,948)	(2,068)	(6,139)	(6,861)
Recoveries	423	405	1,274	1,321
Replenishment of net charge-offs	1,525	1,663	4,865	5,540
Net reserve builds (releases)	258	43	210	(247)
Net specific reserve builds (releases)	(37)	(124)	(53)	(441)
Other	(86)	(368)	(344)	(1,680)
Allowance for loan losses at end of period	12,439	13,626	12,439	13,626
Allowance for loan losses
Determined in accordance with ASC 450					$ 10,245	$ 10,184
Determined in accordance with ASC 310-10-35					2,188	2,426
Determined in accordance with ASC 310-30					6	16
Total allowance for loan losses	12,304	14,075	12,626	15,994	12,439	12,626
Loans, net of unearned income
Loans collectively evaluated for impairment in accordance with ASC 450					623,132	600,367
Loans individually evaluated for impairment in accordance with ASC 310-10-35					11,139	11,995
Loans held at fair value					3,970	5,005
Loans, net of unearned income					638,435	617,617
Receivables Acquired with Deteriorated Credit Quality
Loans, net of unearned income
Loans acquired with deteriorated credit quality in accordance with ASC 310-30					194	250
Corporate
Allowance for credit losses
Allowance for loan losses at beginning of period	2,872	2,406	2,791	2,447
Charge-offs	(63)	(78)	(445)	(230)
Recoveries	23	28	52	80
Replenishment of net charge-offs	40	50	393	150
Net reserve builds (releases)	(110)	116	(122)	196
Net specific reserve builds (releases)	(1)	78	89	(38)
Other	5	(4)	8	(9)
Allowance for loan losses at end of period	2,766	2,596	2,766	2,596
Allowance for loan losses
Determined in accordance with ASC 450					2,285	2,408
Determined in accordance with ASC 310-10-35					481	380
Determined in accordance with ASC 310-30					0	3
Total allowance for loan losses	2,872	2,406	2,791	2,447	2,766	2,791
Loans, net of unearned income
Loans collectively evaluated for impairment in accordance with ASC 450					303,179	285,053
Loans individually evaluated for impairment in accordance with ASC 310-10-35					2,615	1,803
Loans held at fair value					3,939	4,971
Loans, net of unearned income					309,733	291,832
Corporate | Receivables Acquired with Deteriorated Credit Quality
Loans, net of unearned income
Loans acquired with deteriorated credit quality in accordance with ASC 310-30					0	5
Consumer
Allowance for credit losses
Allowance for loan losses at beginning of period	9,432	11,669	9,835	13,547
Charge-offs	(1,885)	(1,990)	(5,694)	(6,631)
Recoveries	400	377	1,222	1,241
Replenishment of net charge-offs	1,485	1,613	4,472	5,390
Net reserve builds (releases)	368	(73)	332	(443)
Net specific reserve builds (releases)	(36)	(202)	(142)	(403)
Other	(91)	(364)	(352)	(1,671)
Allowance for loan losses at end of period	9,673	11,030	9,673	11,030
Allowance for loan losses
Determined in accordance with ASC 450					7,960	7,776
Determined in accordance with ASC 310-10-35					1,707	2,046
Determined in accordance with ASC 310-30					6	13
Total allowance for loan losses	$ 9,432	$ 11,669	$ 9,835	$ 13,547	9,673	9,835
Loans, net of unearned income
Loans collectively evaluated for impairment in accordance with ASC 450					319,953	315,314
Loans individually evaluated for impairment in accordance with ASC 310-10-35					8,524	10,192
Loans held at fair value					31	34
Loans, net of unearned income					328,702	325,785
Consumer | Receivables Acquired with Deteriorated Credit Quality
Loans, net of unearned income
Loans acquired with deteriorated credit quality in accordance with ASC 310-30					$ 194	$ 245