DERIVATIVES - Schedule of Derivative Instruments (Details) - USD ($) $ in Millions		Jun. 30, 2018	Dec. 31, 2017
Derivative Assets
Derivative assets		$ 357	$ 693
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(93)	(72)
Less: Cash collateral applied	[1]	(40)	(4)
Total net derivative fair values presented in the Consolidated Balance Sheets		224	617
Derivative Liabilities
Derivative Liabilities		568	533
Less: Gross amounts offset in the Consolidated Balance Sheets	[1]	(93)	(72)
Less: Cash collateral applied	[1]	(50)	(151)
Total net derivative fair values presented in the Consolidated Balance Sheets		425	310
Derivatives not designated as hedging instruments:
Derivative Assets
Derivative assets		353	693
Derivative Liabilities
Derivative Liabilities		567	533
Interest rate contracts
Derivative Assets
Derivative assets		206	538
Derivative Liabilities
Derivative Liabilities		436	379
Interest rate contracts | Derivatives designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	12,690	13,300
Derivative Assets
Derivative assets		4	0
Derivative Liabilities
Derivative Liabilities		1	0
Interest rate contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	99,182	80,180
Derivative Assets
Derivative assets		202	538
Derivative Liabilities
Derivative Liabilities		435	379
Foreign exchange contracts
Derivative Assets
Derivative assets		143	148
Derivative Liabilities
Derivative Liabilities		126	149
Foreign exchange contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	10,320	9,882
Derivative Assets
Derivative assets		143	148
Derivative Liabilities
Derivative Liabilities		126	149
Other contracts
Derivative Assets
Derivative assets		8	7
Derivative Liabilities
Derivative Liabilities		6	5
Other contracts | Derivatives not designated as hedging instruments:
Derivatives, Fair Value [Line Items]
Notional amount	[2]	1,343	1,039
Derivative Assets
Derivative assets		8	7
Derivative Liabilities
Derivative Liabilities		$ 6	$ 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.