DERIVATIVES - Credit Derivatives (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($) agency	Dec. 31, 2019 USD ($)
Credit Risk Derivatives
Fair values, receivable	$ 10,884	$ 10,409
Fair values, payable	11,494	10,738
Notionals, protection purchased	699,908	703,926
Notionals, protection sold	621,099	603,387
Fair value of derivative in liability position	28,000	30,000
Fair value of collateral already posted	$ 24,000	28,000
Number of rating agencies | agency	3
Additional collateral to be posted	$ 800
Collateral to be segregated	200
Aggregate cash obligations and collateral requirements	1,000
Purchased
Credit Risk Derivatives
Fair values, receivable	6,158	3,415
Fair values, payable	5,655	7,793
Sold
Credit Risk Derivatives
Fair values, receivable	4,726	6,994
Fair values, payable	5,839	2,945
Within 1 year
Credit Risk Derivatives
Fair values, receivable	901	1,806
Fair values, payable	1,785	2,181
Notionals, protection purchased	171,025	231,135
Notionals, protection sold	147,613	176,188
From 1 to 5 years
Credit Risk Derivatives
Fair values, receivable	6,145	7,275
Fair values, payable	6,134	7,265
Notionals, protection purchased	435,061	414,237
Notionals, protection sold	397,139	379,915
After 5 years
Credit Risk Derivatives
Fair values, receivable	3,838	1,328
Fair values, payable	3,575	1,292
Notionals, protection purchased	93,822	58,554
Notionals, protection sold	76,347	47,284
Investment grade
Credit Risk Derivatives
Fair values, receivable	4,116	4,579
Fair values, payable	3,960	4,578
Notionals, protection purchased	551,117	560,806
Notionals, protection sold	479,872	470,778
Non-investment grade
Credit Risk Derivatives
Fair values, receivable	6,768	5,830
Fair values, payable	7,534	6,160
Notionals, protection purchased	148,791	143,120
Notionals, protection sold	141,227	132,609
Credit default swaps and options
Credit Risk Derivatives
Fair values, receivable	10,388	9,759
Fair values, payable	10,272	9,791
Notionals, protection purchased	687,113	685,643
Notionals, protection sold	616,677	593,850
Total return swaps and other
Credit Risk Derivatives
Fair values, receivable	496	650
Fair values, payable	1,222	947
Notionals, protection purchased	12,795	18,283
Notionals, protection sold	4,422	9,537
Banks
Credit Risk Derivatives
Fair values, receivable	3,447	4,017
Fair values, payable	3,624	4,102
Notionals, protection purchased	144,438	172,461
Notionals, protection sold	150,070	169,546
Broker-dealers
Credit Risk Derivatives
Fair values, receivable	2,186	1,724
Fair values, payable	1,457	1,528
Notionals, protection purchased	52,326	54,843
Notionals, protection sold	48,749	53,846
Non-financial
Credit Risk Derivatives
Fair values, receivable	117	92
Fair values, payable	102	76
Notionals, protection purchased	4,615	2,601
Notionals, protection sold	2,423	1,968
Insurance and other financial institutions
Credit Risk Derivatives
Fair values, receivable	5,134	4,576
Fair values, payable	6,311	5,032
Notionals, protection purchased	498,529	474,021
Notionals, protection sold	419,857	378,027
Interest rate swaps
Credit Risk Derivatives
Cash proceeds received for assets derecognized	1,500	5,800
Fair value of derecognized assets	1,600	5,900
Fair value gross derivative assets	41	117
Trading derivatives, liability	$ 23	$ 43