DERIVATIVES - Gains (Losses) Included in Other Revenue (Details) - Other revenue - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative gain (losses)
Gains (losses) included in Other revenue	$ 6	$ 28	$ (222)
Interest rate contracts
Derivative gain (losses)
Gains (losses) included in Other revenue	63	57	(25)
Foreign exchange contracts
Derivative gain (losses)
Gains (losses) included in Other revenue	$ (57)	$ (29)	$ (197)

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL109998890-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959

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