ALLOWANCE FOR CREDIT LOSSES - Allowance for Loan Losses Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Allowance for credit losses
Allowance for loan losses at beginning of period	$ 12,030	$ 12,712	$ 12,060	$ 12,626
Gross credit losses	(2,130)	(2,048)	(4,274)	(4,191)
Gross recoveries	420	432	855	851
Net credit losses (NCLs)	(1,710)	(1,616)	(3,419)	(3,340)
Net credit losses (NCLs)	1,710	1,616	3,419	3,340
Net reserve builds (releases)	67	(90)	47	(48)
Net specific reserve releases	(111)	(136)	(125)	(16)
Total provision for loan losses	1,666	1,390	3,341	3,276
Other, net	39	(182)	43	(258)
Allowance for loan losses at end of period	12,025	12,304	12,025	12,304
Allowance for credit losses on unfunded lending commitments
Allowance for credit losses on unfunded lending commitments at beginning of period	1,377	1,473	1,418	1,402
Provision (release) for unfunded lending commitments	28	(30)	(15)	41
Other, net	1	(11)	3	(11)
Allowance for credit losses on unfunded lending commitments at end of period	1,406	1,432	1,406	1,432
Total allowance for loans, leases and unfunded lending commitments	13,431	13,736	13,431	13,736
Sales or transfers of various consumer loan portfolios to held-for-sale
Other, net	39	(182)	43	(258)
Consumer
Sales or transfers of various consumer loan portfolios to held-for-sale
Transfer of real estate loan portfolios	(19)	(24)	(56)	(53)
Transfer of other loan portfolios	0	(77)	(124)	(196)
Sales or transfers of various consumer loan portfolios to held-for-sale	(19)	(101)	(180)	(249)
FX translation, consumer	50	(75)	214	(12)
Corporate
Allowance for credit losses
Other, net	8	(6)	9	3
Sales or transfers of various consumer loan portfolios to held-for-sale
Other, net	$ 8	$ (6)	$ 9	$ 3