DERIVATIVES ACTIVITIES - Credit Derivatives (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) agency	Dec. 31, 2017 USD ($)
Credit Risk Derivatives
Fair values, Receivable	$ 19,027	$ 20,534
Fair values, Payable	19,609	21,533
Notionals, Protection purchased	790,134	777,713
Notionals, Protection sold	741,700	735,142
Fair value of derivative in liability position	29,000	29,000
Fair value of collateral already posted	$ 26,000	28,000
Number of rating agencies | agency	3
Additional collateral to be posted	$ 700
Collateral to be segregated	200
Aggregate cash obligations and collateral requirements	900
Purchased
Credit Risk Derivatives
Fair values, Receivable	3,016	3,195
Fair values, Payable	16,793	3,147
Sold
Credit Risk Derivatives
Fair values, Receivable	16,011	17,339
Fair values, Payable	2,816	18,386
Within 1 year
Credit Risk Derivatives
Fair values, Receivable	2,337	2,477
Fair values, Payable	2,517	2,914
Notionals, Protection purchased	228,396	231,878
Notionals, Protection sold	212,661	218,097
From 1 to 5 years
Credit Risk Derivatives
Fair values, Receivable	14,152	16,098
Fair values, Payable	14,223	16,435
Notionals, Protection purchased	477,627	498,606
Notionals, Protection sold	454,001	476,345
After 5 years
Credit Risk Derivatives
Fair values, Receivable	2,538	1,959
Fair values, Payable	2,869	2,184
Notionals, Protection purchased	84,111	47,229
Notionals, Protection sold	75,038	40,700
Investment grade
Credit Risk Derivatives
Fair values, Receivable	9,496	10,473
Fair values, Payable	9,594	10,616
Notionals, Protection purchased	597,093	588,324
Notionals, Protection sold	559,526	557,987
Non-investment grade
Credit Risk Derivatives
Fair values, Receivable	9,531	10,061
Fair values, Payable	10,015	10,917
Notionals, Protection purchased	193,041	189,389
Notionals, Protection sold	182,174	177,155
Credit default swaps and options
Credit Risk Derivatives
Fair values, Receivable	18,591	20,251
Fair values, Payable	18,787	20,554
Notionals, Protection purchased	766,018	754,114
Notionals, Protection sold	729,303	724,228
Total return swaps and other
Credit Risk Derivatives
Fair values, Receivable	436	283
Fair values, Payable	822	979
Notionals, Protection purchased	24,116	23,599
Notionals, Protection sold	12,397	10,914
Banks
Credit Risk Derivatives
Fair values, Receivable	6,782	7,471
Fair values, Payable	6,120	6,669
Notionals, Protection purchased	263,672	264,414
Notionals, Protection sold	272,815	273,711
Broker-dealers
Credit Risk Derivatives
Fair values, Receivable	2,155	2,325
Fair values, Payable	2,060	2,285
Notionals, Protection purchased	72,862	73,273
Notionals, Protection sold	83,585	83,229
Non-financial
Credit Risk Derivatives
Fair values, Receivable	75	70
Fair values, Payable	75	91
Notionals, Protection purchased	1,240	1,288
Notionals, Protection sold	2,313	1,140
Insurance and other financial institutions
Credit Risk Derivatives
Fair values, Receivable	10,015	10,668
Fair values, Payable	11,354	12,488
Notionals, Protection purchased	452,360	438,738
Notionals, Protection sold	382,987	377,062
Interest rate swaps
Credit Risk Derivatives
Cash proceeds received for assets derecognized	3,400	3,000
Fair value of derecognized assets	3,400	3,100
Fair value gross derivative assets	79	89
Trading derivatives, liability	$ 52	$ 15