DERIVATIVES ACTIVITIES - Gains (Losses) Included in Other Revenue (Details) - Other revenue - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	$ (31)	$ 499
Interest rate contracts
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	27	(28)
Foreign exchange contracts
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	$ (58)	$ 527