RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - ADDITIONAL INFORMATION (Details) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	$ 19,870	$ 24,362
Long Term Debt, Current Maturities Measured at Fair Value	1,790	2,761
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term Debt, Fair Value	1,700	2,331
U.S. Government Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	1,642	292
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	3,983	4,513
Corporate Bond Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis	443	382
Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis	$ 1,369	$ 1,018