DERIVATIVES - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Derivative Assets
Derivative assets		$ 300	$ 693
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(85)	(72)
Less: Cash collateral applied	[1]	(42)	(4)
Total net derivative fair values presented in the Consolidated Balance Sheets		173	617
Derivative Liabilities
Derivative Liabilities		575	533
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(85)	(72)
Less: Cash collateral applied	[1]	(41)	(151)
Total net derivative fair values presented in the Consolidated Balance Sheets		449	310
Derivatives not designated as hedging instruments:
Derivative Assets
Derivative assets		295	693
Derivative Liabilities
Derivative Liabilities		575	533
Interest rate contracts
Derivative Assets
Derivative assets		165	538
Derivative Liabilities
Derivative Liabilities		469	379
Interest rate contracts | Derivatives designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	10,050	13,300
Derivative Assets
Derivative assets		5	0
Derivative Liabilities
Derivative Liabilities		0	0
Interest rate contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	111,837	80,180
Derivative Assets
Derivative assets		160	538
Derivative Liabilities
Derivative Liabilities		469	379
Foreign exchange contracts
Derivative Assets
Derivative assets		116	148
Derivative Liabilities
Derivative Liabilities		105	149
Foreign exchange contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	10,346	9,882
Derivative Assets
Derivative assets		116	148
Derivative Liabilities
Derivative Liabilities		105	149
Other contracts
Derivative Assets
Derivative assets		19	7
Derivative Liabilities
Derivative Liabilities		1	5
Other contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	5,201	1,039
Derivative Assets
Derivative assets		19	7
Derivative Liabilities
Derivative Liabilities		$ 1	$ 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.