DERIVATIVES ACTIVITIES - Credit Derivatives (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) counterparty agency	Dec. 31, 2016 USD ($)
Credit Derivative
Percentage of receivables from counterparties with collateral agreements	98.00%	98.00%
Number of top counterparties which are banks, financial institutions, and other dealers | counterparty	15
Fair value, Receivable	$ 20,534	$ 24,821
Fair Value, Payable	21,533	25,825
Notionals, Protection purchased	777,713	902,473
Notionals, Protection sold	735,142	859,420
Fair value of derivative in liability position	29,000	26,000
Fair value of collateral already posted	$ 28,000	26,000
Number of rating agencies | agency	3
Additional collateral to be posted	$ 900
Collateral to be segregated	300
Aggregate cash obligations and collateral requirements	1,200
Purchased
Credit Derivative
Fair value, Receivable	3,195	9,077
Fair Value, Payable	3,147	17,110
Sold
Credit Derivative
Fair value, Receivable	17,339	15,744
Fair Value, Payable	18,386	8,715
Within 1 year
Credit Derivative
Fair value, Receivable	2,477	4,113
Fair Value, Payable	2,914	4,841
Notionals, Protection purchased	231,878	293,059
Notionals, Protection sold	218,097	287,262
From 1 to 5 years
Credit Derivative
Fair value, Receivable	16,098	17,735
Fair Value, Payable	16,435	17,986
Notionals, Protection purchased	498,606	551,155
Notionals, Protection sold	476,345	523,371
After 5 years
Credit Derivative
Fair value, Receivable	1,959	2,973
Fair Value, Payable	2,184	2,998
Notionals, Protection purchased	47,229	58,259
Notionals, Protection sold	40,700	48,787
Investment Grade
Credit Derivative
Fair value, Receivable	10,473	9,605
Fair Value, Payable	10,616	9,995
Notionals, Protection purchased	588,324	675,138
Notionals, Protection sold	557,987	648,247
Non-Investment Grade
Credit Derivative
Fair value, Receivable	10,061	15,216
Fair Value, Payable	10,917	15,830
Notionals, Protection purchased	189,389	227,335
Notionals, Protection sold	177,155	211,173
Credit default swaps and options
Credit Derivative
Fair value, Receivable	20,251	24,502
Fair Value, Payable	20,554	24,631
Notionals, Protection purchased	754,114	883,719
Notionals, Protection sold	724,228	852,900
Total return swaps and other
Credit Derivative
Fair value, Receivable	283	319
Fair Value, Payable	979	1,194
Notionals, Protection purchased	23,599	18,754
Notionals, Protection sold	10,914	6,520
Bank
Credit Derivative
Fair value, Receivable	7,471	11,895
Fair Value, Payable	6,669	10,930
Notionals, Protection purchased	264,414	407,992
Notionals, Protection sold	273,711	414,720
Broker-dealer
Credit Derivative
Fair value, Receivable	2,325	3,536
Fair Value, Payable	2,285	3,952
Notionals, Protection purchased	73,273	115,013
Notionals, Protection sold	83,229	119,810
Non-financial
Credit Derivative
Fair value, Receivable	70	82
Fair Value, Payable	91	99
Notionals, Protection purchased	1,288	4,014
Notionals, Protection sold	1,140	2,061
Insurance and other financial institutions
Credit Derivative
Fair value, Receivable	10,668	9,308
Fair Value, Payable	12,488	10,844
Notionals, Protection purchased	438,738	375,454
Notionals, Protection sold	377,062	322,829
Interest rate swaps
Credit Derivative
Amount derecognized	3,000	1,000
Cash proceeds received for assets derecognized	3,000	1,000
Fair value of derecognized assets	3,100	1,000
Fair value gross derivative assets	89	32
Trading derivatives, liability	$ 15	$ 23