RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - GAIN (LOSS) ON DERIVATIVE INSTRUMENTS (EFFECTIVE PORTION) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016
Derivatives in Cash Flow Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivatives (Effective Portion)	$ (9)	$ (2)
Derivatives in Cash Flow Hedging Relationships | Interest Rate Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivatives (Effective Portion)	(2)	(2)
Derivatives in Cash Flow Hedging Relationships | Foreign Currency Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivatives (Effective Portion)	(7)	0
Derivatives in Net Investment Hedging Relationships
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain/(Loss) Recognized in AOCI on Derivatives (Effective Portion)	$ 94	$ (53)