DERIVATIVES - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Derivative Assets
Derivative assets		$ 449	$ 693
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(87)	(72)
Less: Cash collateral applied	[1]	(45)	(4)
Total net derivative fair values presented in the Consolidated Balance Sheets		317	617
Derivative Liabilities
Derivative Liabilities		415	533
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(87)	(72)
Less: Cash collateral applied	[1]	(36)	(151)
Total net derivative fair values presented in the Consolidated Balance Sheets		292	310
Derivatives not designated as hedging instruments:
Derivative Assets
Derivative assets		444	693
Derivative Liabilities
Derivative Liabilities		415	533
Interest rate swaps
Derivative Assets
Derivative assets		306	538
Derivative Liabilities
Derivative Liabilities		277	379
Interest rate swaps | Derivatives designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	12,050	13,300
Derivative Assets
Derivative assets		5	0
Derivative Liabilities
Derivative Liabilities		0	0
Interest rate swaps | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	117,076	80,180
Derivative Assets
Derivative assets		301	538
Derivative Liabilities
Derivative Liabilities		277	379
Foreign exchange contracts
Derivative Assets
Derivative assets		129	148
Derivative Liabilities
Derivative Liabilities		113	149
Foreign exchange contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	9,866	9,882
Derivative Assets
Derivative assets		129	148
Derivative Liabilities
Derivative Liabilities		113	149
Other contracts
Derivative Assets
Derivative assets		14	7
Derivative Liabilities
Derivative Liabilities		25	5
Other contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	3,555	1,039
Derivative Assets
Derivative assets		14	7
Derivative Liabilities
Derivative Liabilities		$ 25	$ 5

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

[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.