ALLOWANCE FOR CREDIT LOSSES - Allowance for Loan Losses Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Allowance for credit losses
Allowance for loan losses at beginning of period	$ 12,060	$ 12,626
Gross credit losses	(2,144)	(2,143)
Gross recoveries	435	419
Net credit losses (NCLs)	(1,709)	(1,724)
Net credit losses (NCLs)	1,709	1,724
Net reserve builds (releases)	(20)	42
Net specific reserve builds (releases)	(14)	120
Total provision for loan losses	1,675	1,886
Other, net	4	(76)
Allowance for loan losses at end of period	12,030	12,712
Allowance for credit losses on unfunded lending commitments
Allowance for credit losses on unfunded lending commitments at beginning of period	1,418	1,402
Provision (release) for unfunded lending commitments	(43)	71
Other, net	2	0
Allowance for credit losses on unfunded lending commitments at end of period	1,377	1,473
Total allowance for loans, leases, and unfunded lending commitments	13,407	14,185
Sales or transfers of various consumer loan portfolios to held-for-sale
Other, net	4	(76)
Consumer
Sales or transfers of various consumer loan portfolios to held-for-sale
Transfer of real estate loan portfolios	(37)	(29)
Transfer of other loan portfolios	(124)	(119)
Sales or transfers of various consumer loan portfolios to held-for-sale	(161)	(148)
FX translation, consumer	164	63
Corporate
Allowance for credit losses
Other, net	1	9
Sales or transfers of various consumer loan portfolios to held-for-sale
Other, net	$ 1	$ 9