DERIVATIVES ACTIVITIES - Credit Derivatives (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) counterparty agency	Dec. 31, 2018 USD ($)
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	$ 10,409	$ 10,765
Fair Value, Payable	10,738	10,351
Notionals, Protection purchased	703,926	795,649
Notionals, Protection sold	603,387	724,939
Fair value of derivative in liability position	30,000	33,000
Fair value of collateral already posted	$ 28,000	33,000
Number of rating agencies | agency	3
Additional collateral to be posted	$ 600
Collateral to be segregated	200
Aggregate cash obligations and collateral requirements	800
Purchased
Credit Derivative
Fair value, Receivable	3,415	5,126
Fair Value, Payable	7,793	5,882
Sold
Credit Derivative
Fair value, Receivable	6,994	5,639
Fair Value, Payable	2,945	4,469
Within 1 year
Credit Derivative
Fair value, Receivable	1,806	2,037
Fair Value, Payable	2,181	2,063
Notionals, Protection purchased	231,135	251,994
Notionals, Protection sold	176,188	225,597
From 1 to 5 years
Credit Derivative
Fair value, Receivable	7,275	6,720
Fair Value, Payable	7,265	6,414
Notionals, Protection purchased	414,237	493,096
Notionals, Protection sold	379,915	456,409
After 5 years
Credit Derivative
Fair value, Receivable	1,328	2,008
Fair Value, Payable	1,292	1,874
Notionals, Protection purchased	58,554	50,559
Notionals, Protection sold	47,284	42,933
Investment Grade
Credit Derivative
Fair value, Receivable	4,579	4,725
Fair Value, Payable	4,578	4,544
Notionals, Protection purchased	560,806	637,790
Notionals, Protection sold	470,778	568,849
Non-Investment Grade
Credit Derivative
Fair value, Receivable	5,830	6,040
Fair Value, Payable	6,160	5,807
Notionals, Protection purchased	143,120	157,859
Notionals, Protection sold	132,609	156,090
Credit default swaps and options
Credit Derivative
Fair value, Receivable	9,759	10,030
Fair Value, Payable	9,791	9,755
Notionals, Protection purchased	685,643	771,865
Notionals, Protection sold	593,850	712,623
Total return swaps and other
Credit Derivative
Fair value, Receivable	650	735
Fair Value, Payable	947	596
Notionals, Protection purchased	18,283	23,784
Notionals, Protection sold	9,537	12,316
Banks
Credit Derivative
Fair value, Receivable	4,017	4,785
Fair Value, Payable	4,102	4,432
Notionals, Protection purchased	172,461	214,842
Notionals, Protection sold	169,546	218,273
Broker-dealers
Credit Derivative
Fair value, Receivable	1,724	1,706
Fair Value, Payable	1,528	1,612
Notionals, Protection purchased	54,843	62,904
Notionals, Protection sold	53,846	63,014
Non-financial
Credit Derivative
Fair value, Receivable	92	64
Fair Value, Payable	76	87
Notionals, Protection purchased	2,601	2,687
Notionals, Protection sold	1,968	1,192
Insurance and other financial institutions
Credit Derivative
Fair value, Receivable	4,576	4,210
Fair Value, Payable	5,032	4,220
Notionals, Protection purchased	474,021	515,216
Notionals, Protection sold	378,027	442,460
Interest rate swaps
Credit Derivative
Amount derecognized	3,700	4,600
Cash proceeds received for assets derecognized	5,800	4,600
Fair value of derecognized assets	5,900	4,500
Fair value gross derivative assets	117	55
Trading derivatives, liability	$ 43	$ 40