PRINCIPAL TRANSACTIONS (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Principal transactions revenue
Principal transactions revenue	$ 1,874	$ 2,126	$ 4,678	$ 5,368
Interest rate risks
Principal transactions revenue
Principal transactions revenue	1,320	1,550	3,038	3,116
Foreign exchange risks
Principal transactions revenue
Principal transactions revenue	427	175	900	905
Equity risks
Principal transactions revenue
Principal transactions revenue	(1)	120	455	709
Commodity and other risks
Principal transactions revenue
Principal transactions revenue	89	208	208	309
Credit products and risks
Principal transactions revenue
Principal transactions revenue	$ 39	$ 73	$ 77	$ 329