DERIVATIVES - Effect of Customer Derivatives and Economic Hedges on Net Income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total		$ 32	$ 33	$ 70
Other Income | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total		(2)	(4)
Customer derivative contracts | Other Income | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total	[1]	140	240	79
Customer derivative contracts | Other Income | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total	[1]	(18)	(59)	18
Customer derivative contracts | Mortgage Banking Fees | Residential loan commitments
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total	[2]	(4)	6	(7)
Economic hedges | Other Income | Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total	[1]	(106)	(209)	(30)
Economic hedges | Foreign Exchange and Trade Finance Fees | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total	[3]	19	58	(15)
Economic hedges | Mortgage Banking Fees | Forward sale contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amounts Recognized in Noninterest Income, Total	[2]	$ 1	$ (3)	$ 25

[1] Reported in other income on the Consolidated Statements of Operations.

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

[3] Reported in foreign exchange and trade finance fees on the Consolidated Statements of Operations.