DERIVATIVES - Gains (Losses) Included in Other Revenue (Details) - Other revenue - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	$ (28)	$ (42)	$ (109)	$ 137
Interest rate contracts
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	(15)	19	(75)	174
Foreign exchange contracts
Derivative gain (losses)
Gains (losses) recognized in Other revenue related to derivatives not designated in a qualifying hedging relationship	$ (13)	$ (61)	$ (34)	$ (37)