DERIVATIVES - Effect of Customer Derivatives and Economic Hedges on Net Income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income		$ 66	$ 65	$ 32
Customer derivative contracts | Foreign exchange and trade finance fees | Interest rate contract
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	5	(23)	140
Customer derivative contracts | Foreign exchange and trade finance fees | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	172	(81)	(18)
Customer derivative contracts | Mortgage banking fees | Residential loan commitments
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[2]	2	(2)	(4)
Economic hedges | Foreign exchange and trade finance fees | Interest rate contract
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	46	70	(106)
Economic hedges | Foreign exchange and trade finance fees | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	(151)	95	19
Economic hedges | Mortgage banking fees | Forward sale contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[2]	$ (8)	$ 6	$ 1

[1] Reported in foreign exchange and interest rate products on the Consolidated Statements of Operations.

[2] Reported in mortgage banking fees on the Consolidated Statements of Operations.