DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Schedule of Derivative Assets and Liabilities and Locations on Consolidated Balance Sheet (Details) - Recurring - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative asset	$ 1	$ 55
Derivative liability	117	11
Current Assets: Other current assets
Derivatives, Fair Value [Line Items]
Derivative asset	1	55
Current Liabilities: Other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liability	23	11
Deferred Credits and Other Noncurrent Liabilities: Other
Derivatives, Fair Value [Line Items]
Derivative liability	94	0
Commodity Derivative Instruments
Derivatives, Fair Value [Line Items]
Derivative asset	1	55
Derivative liability	$ 23	$ 11