DERIVATIVES - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions		Dec. 31, 2017		Dec. 31, 2016
Derivative Assets
Derivative assets		$ 693	[1]	$ 759
Less: Gross amounts offset in the Consolidated Balance Sheets	[2]	(72)	[1]	(106)
Less: Cash collateral applied	[2]	(4)	[1]	(26)
Total net derivative fair values presented in the Consolidated Balance Sheets		617	[1]	627
Derivative Liabilities
Derivative Liabilities		533	[1]	778
Less: Gross amounts offset in the Consolidated Balance Sheets	[2]	(72)	[1]	(106)
Less: Cash collateral applied	[2]	(151)	[1]	(13)
Total net derivative fair values presented in the Consolidated Balance Sheets		310	[1]	659
Derivatives not designated as hedging instruments:
Derivative Assets
Derivative assets		693	[1]	707
Derivative Liabilities
Derivative Liabilities		533	[1]	585
Interest rate swaps
Derivative Assets
Derivative assets		538		609
Derivative Liabilities
Derivative Liabilities		379		645
Interest rate swaps | Derivatives designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[3]	13,300		13,350
Derivative Assets
Derivative assets		0	[1]	52
Derivative Liabilities
Derivative Liabilities		0	[1]	193
Interest rate swaps | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[3]	80,180		54,656
Derivative Assets
Derivative assets		538	[1]	557
Derivative Liabilities
Derivative Liabilities		379	[1]	452
Foreign exchange contracts
Derivative Assets
Derivative assets		148		134
Derivative Liabilities
Derivative Liabilities		149		126
Foreign exchange contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[3]	9,882		8,039
Derivative Assets
Derivative assets		148	[1]	134
Derivative Liabilities
Derivative Liabilities		149	[1]	126
Other contracts
Derivative Assets
Derivative assets		7		16
Derivative Liabilities
Derivative Liabilities		5		7
Other contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[3]	1,039		1,498
Derivative Assets
Derivative assets		7	[1]	16
Derivative Liabilities
Derivative Liabilities		$ 5	[1]	$ 7

[1] Amounts reflect changes in the treatment of variation margin on certain centrally cleared derivatives.

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

[3] 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.