DERIVATIVES - Credit Derivatives (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) agency	Dec. 31, 2019 USD ($)
Credit Risk Derivatives
Fair values, Receivable	$ 16,481	$ 10,409
Fair values, Payable	15,173	10,738
Notionals, Protection purchased	695,218	703,926
Notionals, Protection sold	624,063	603,387
Fair value of derivative in liability position	34,000	30,000
Fair value of collateral already posted	$ 29,000	28,000
Number of rating agencies | agency	3
Additional collateral to be posted	$ 1,000
Collateral to be segregated	200
Aggregate cash obligations and collateral requirements	1,200
Purchased
Credit Risk Derivatives
Fair values, Receivable	13,355	3,415
Fair values, Payable	4,088	7,793
Sold
Credit Risk Derivatives
Fair values, Receivable	3,126	6,994
Fair values, Payable	11,805	2,945
Within 1 year
Credit Risk Derivatives
Fair values, Receivable	2,913	1,806
Fair values, Payable	2,752	2,181
Notionals, Protection purchased	170,955	231,135
Notionals, Protection sold	148,981	176,188
From 1 to 5 years
Credit Risk Derivatives
Fair values, Receivable	9,195	7,275
Fair values, Payable	8,467	7,265
Notionals, Protection purchased	429,874	414,237
Notionals, Protection sold	391,944	379,915
After 5 years
Credit Risk Derivatives
Fair values, Receivable	4,373	1,328
Fair values, Payable	3,954	1,292
Notionals, Protection purchased	94,389	58,554
Notionals, Protection sold	83,138	47,284
Investment grade
Credit Risk Derivatives
Fair values, Receivable	5,708	4,579
Fair values, Payable	5,243	4,578
Notionals, Protection purchased	542,640	560,806
Notionals, Protection sold	481,482	470,778
Non-investment grade
Credit Risk Derivatives
Fair values, Receivable	10,773	5,830
Fair values, Payable	9,930	6,160
Notionals, Protection purchased	152,578	143,120
Notionals, Protection sold	142,581	132,609
Credit default swaps and options
Credit Risk Derivatives
Fair values, Receivable	14,555	9,759
Fair values, Payable	13,459	9,791
Notionals, Protection purchased	679,118	685,643
Notionals, Protection sold	618,108	593,850
Total return swaps and other
Credit Risk Derivatives
Fair values, Receivable	1,926	650
Fair values, Payable	1,714	947
Notionals, Protection purchased	16,100	18,283
Notionals, Protection sold	5,955	9,537
Banks
Credit Risk Derivatives
Fair values, Receivable	5,665	4,017
Fair values, Payable	5,633	4,102
Notionals, Protection purchased	162,933	172,461
Notionals, Protection sold	167,923	169,546
Broker-dealers
Credit Risk Derivatives
Fair values, Receivable	3,400	1,724
Fair values, Payable	2,947	1,528
Notionals, Protection purchased	63,281	54,843
Notionals, Protection sold	63,382	53,846
Non-financial
Credit Risk Derivatives
Fair values, Receivable	140	92
Fair values, Payable	82	76
Notionals, Protection purchased	4,223	2,601
Notionals, Protection sold	1,825	1,968
Insurance and other financial institutions
Credit Risk Derivatives
Fair values, Receivable	7,276	4,576
Fair values, Payable	6,511	5,032
Notionals, Protection purchased	464,781	474,021
Notionals, Protection sold	390,933	378,027
Interest rate swaps
Credit Risk Derivatives
Cash proceeds received for assets derecognized	2,400	5,800
Fair value of derecognized assets	2,400	5,900
Fair value gross derivative assets	56	117
Trading derivatives, liability	$ 115	$ 43