PRINCIPAL TRANSACTIONS (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Principal transactions revenue
Principal transactions revenue	$ 2,566	$ 2,248	$ 8,006	$ 7,985
Interest rate risks
Principal transactions revenue
Principal transactions revenue	1,403	1,180	4,576	4,421
Foreign exchange risks
Principal transactions revenue
Principal transactions revenue	467	606	1,387	1,942
Equity risks
Principal transactions revenue
Principal transactions revenue	311	154	997	440
Commodity and other risks
Principal transactions revenue
Principal transactions revenue	244	112	544	434
Credit products and risks
Principal transactions revenue
Principal transactions revenue	$ 141	$ 196	$ 502	$ 748