RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - DERIVATIVE NOTIONAL AMOUNTS AND FAIR VALUE - ADDITIONAL INFORMATION (Details) (Details) - USD ($) $ in Millions		Sep. 30, 2017	Jun. 30, 2017
Underlying, Other | Derivatives in Fair Value Hedging Relationships
Derivative [Line Items]
Notional Amount	[1]	$ 4,764	$ 4,705

[1] The fair value of the derivative asset/liability directly offsets the cumulative amount of the fair value hedging adjustment included in the carrying amount of the underlying debt obligation. The carrying amount of the underlying debt obligation, net of the fair value adjustment, was $4,764 as of September 30, 2017 and $4,705 as of June 30, 2017, respectively.