DERIVATIVES - Gains (Losses) Included in Other Revenue (Details) - Other revenue - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	$ 106	$ (532)	$ 75	$ (30)
Interest rate contracts
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	35	(15)	62	(43)
Foreign exchange contracts
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	$ 71	$ (517)	$ 13	$ 13