DERIVATIVES - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Derivative Assets
Derivative assets		$ 369	$ 693
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(83)	(72)
Less: Cash collateral applied	[1]	(12)	(4)
Total net derivative fair values presented in the Consolidated Balance Sheets		274	617
Derivative Liabilities
Derivative Liabilities		532	533
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(83)	(72)
Less: Cash collateral applied	[1]	(118)	(151)
Total net derivative fair values presented in the Consolidated Balance Sheets		331	310
Derivatives not designated as hedging instruments:
Derivative Assets
Derivative assets		369	693
Derivative Liabilities
Derivative Liabilities		532	533
Interest rate contracts
Derivative Assets
Derivative assets		204	538
Derivative Liabilities
Derivative Liabilities		377	379
Interest rate contracts | Derivatives designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	11,550	13,300
Derivative Assets
Derivative assets		0	0
Derivative Liabilities
Derivative Liabilities		0	0
Interest rate contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	88,089	80,180
Derivative Assets
Derivative assets		204	538
Derivative Liabilities
Derivative Liabilities		377	379
Foreign exchange contracts
Derivative Assets
Derivative assets		158	148
Derivative Liabilities
Derivative Liabilities		150	149
Foreign exchange contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	9,525	9,882
Derivative Assets
Derivative assets		158	148
Derivative Liabilities
Derivative Liabilities		150	149
Other contracts
Derivative Assets
Derivative assets		7	7
Derivative Liabilities
Derivative Liabilities		5	5
Other contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	1,142	1,039
Derivative Assets
Derivative assets		7	7
Derivative Liabilities
Derivative Liabilities		$ 5	$ 5

[1] Amounts represent the impact of enforceable master netting agreements that allow the Company to net settle positive and negative positions.

[2] The notional or contractual amount of interest rate derivatives and foreign exchange contracts is the amount upon which interest and other payments under the contract are based. For interest rate contracts, the notional amount is typically not exchanged. Therefore, notional amounts should not be taken as the measure of credit or market risk, as they do not measure the true economic risk of these contracts.