PRINCIPAL TRANSACTIONS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Principal transactions revenue
Principal transactions revenue	$ 2,804	$ 3,242
Interest rate risks
Principal transactions revenue
Principal transactions revenue	1,718	1,566
Foreign exchange risks
Principal transactions revenue
Principal transactions revenue	473	730
Equity risks
Principal transactions revenue
Principal transactions revenue	456	589
Commodity and other risks
Principal transactions revenue
Principal transactions revenue	119	101
Credit products and risks
Principal transactions revenue
Principal transactions revenue	$ 38	$ 256