DERIVATIVES - Credit Derivatives (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) agency	Dec. 31, 2018 USD ($)
Credit Risk Derivatives
Fair values, Receivable	$ 11,309	$ 10,765
Fair values, Payable	12,361	10,351
Notionals, Protection purchased	773,629	795,649
Notionals, Protection sold	680,809	724,939
Fair value of derivative in liability position	32,000	33,000
Fair value of collateral already posted	$ 29,000	33,000
Number of rating agencies | agency	3
Additional collateral to be posted	$ 1,000
Collateral to be segregated	100
Aggregate cash obligations and collateral requirements	900
Purchased
Credit Risk Derivatives
Fair values, Receivable	4,247	5,126
Fair values, Payable	8,551	5,882
Sold
Credit Risk Derivatives
Fair values, Receivable	7,062	5,639
Fair values, Payable	3,810	4,469
Within 1 year
Credit Risk Derivatives
Fair values, Receivable	1,504	2,037
Fair values, Payable	2,432	2,063
Notionals, Protection purchased	223,743	251,994
Notionals, Protection sold	175,978	225,597
From 1 to 5 years
Credit Risk Derivatives
Fair values, Receivable	7,927	6,720
Fair values, Payable	8,170	6,414
Notionals, Protection purchased	453,995	493,096
Notionals, Protection sold	418,675	456,409
After 5 years
Credit Risk Derivatives
Fair values, Receivable	1,878	2,008
Fair values, Payable	1,759	1,874
Notionals, Protection purchased	95,891	50,559
Notionals, Protection sold	86,156	42,933
Investment grade
Credit Risk Derivatives
Fair values, Receivable	5,992	4,725
Fair values, Payable	5,976	4,544
Notionals, Protection purchased	597,001	637,790
Notionals, Protection sold	519,575	568,849
Non-investment grade
Credit Risk Derivatives
Fair values, Receivable	5,317	6,040
Fair values, Payable	6,385	5,807
Notionals, Protection purchased	176,628	157,859
Notionals, Protection sold	161,234	156,090
Credit default swaps and options
Credit Risk Derivatives
Fair values, Receivable	10,449	10,030
Fair values, Payable	10,438	9,755
Notionals, Protection purchased	749,061	771,865
Notionals, Protection sold	669,514	712,623
Total return swaps and other
Credit Risk Derivatives
Fair values, Receivable	860	735
Fair values, Payable	1,923	596
Notionals, Protection purchased	24,568	23,784
Notionals, Protection sold	11,295	12,316
Banks
Credit Risk Derivatives
Fair values, Receivable	4,450	4,785
Fair values, Payable	4,333	4,432
Notionals, Protection purchased	183,263	214,842
Notionals, Protection sold	188,606	218,273
Broker-dealers
Credit Risk Derivatives
Fair values, Receivable	1,929	1,706
Fair values, Payable	1,634	1,612
Notionals, Protection purchased	63,607	62,904
Notionals, Protection sold	63,261	63,014
Non-financial
Credit Risk Derivatives
Fair values, Receivable	93	64
Fair values, Payable	86	87
Notionals, Protection purchased	2,917	2,687
Notionals, Protection sold	1,905	1,192
Insurance and other financial institutions
Credit Risk Derivatives
Fair values, Receivable	4,837	4,210
Fair values, Payable	6,308	4,220
Notionals, Protection purchased	523,842	515,216
Notionals, Protection sold	427,037	442,460
Interest rate swaps
Credit Risk Derivatives
Cash proceeds received for assets derecognized	3,400	4,600
Fair value of derecognized assets	3,400	4,500
Fair value gross derivative assets	31	55
Trading derivatives, liability	$ 13	$ 40