DERIVATIVES - Effect of Customer Derivatives and Economic Hedges on Net Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income		$ 22	$ 11	$ 32	$ 17
Customer derivative contracts | Foreign Exchange and Interest Rate Products | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	83	(2)	80	95
Customer derivative contracts | Foreign Exchange and Interest Rate Products | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	78	(23)	96	28
Customer derivative contracts | Mortgage Banking Fees | Residential loan commitments
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[2]	(2)	3	3	7
Economic hedges | Foreign Exchange and Interest Rate Products | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	(71)	15	(56)	(76)
Economic hedges | Foreign Exchange and Interest Rate Products | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[1]	(71)	23	(85)	(27)
Economic hedges | Mortgage Banking Fees | Forward sale contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income	[2]	$ 5	$ (5)	$ (6)	$ (10)

[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.