DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES - Schedule of Derivative Assets and Liabilities Measured at Fair Value (Details) - Recurring - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative asset	$ 37	$ 55
Derivative liability	38	11
Commodity Derivative Instruments
Derivative [Line Items]
Derivative asset, fair value	50	69
Derivative asset, netting	(14)	(14)
Derivative asset	36	55
Derivative liability, fair value	46	25
Derivative liability, netting	(14)	(14)
Derivative liability	32	11
Commodity Derivative Instruments | Quoted Price in Active Markets (Level 1)
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivative liability, fair value	0	0
Commodity Derivative Instruments | Significant Other Inputs (Level 2)
Derivative [Line Items]
Derivative asset, fair value	50	69
Derivative liability, fair value	46	25
Commodity Derivative Instruments | Significant Unobservable Inputs (Level 3)
Derivative [Line Items]
Derivative asset, fair value	0	0
Derivative liability, fair value	0	$ 0
Foreign Currency Derivative Instruments
Derivative [Line Items]
Derivative asset, fair value	1
Derivative asset, netting	0
Derivative asset	1
Foreign Currency Derivative Instruments | Quoted Price in Active Markets (Level 1)
Derivative [Line Items]
Derivative asset, fair value	0
Foreign Currency Derivative Instruments | Significant Other Inputs (Level 2)
Derivative [Line Items]
Derivative asset, fair value	1
Foreign Currency Derivative Instruments | Significant Unobservable Inputs (Level 3)
Derivative [Line Items]
Derivative asset, fair value	0
Interest Rate Derivative Instruments
Derivative [Line Items]
Derivative liability, fair value	6
Derivative liability, netting	0
Derivative liability	6
Interest Rate Derivative Instruments | Quoted Price in Active Markets (Level 1)
Derivative [Line Items]
Derivative liability, fair value	0
Interest Rate Derivative Instruments | Significant Other Inputs (Level 2)
Derivative [Line Items]
Derivative liability, fair value	6
Interest Rate Derivative Instruments | Significant Unobservable Inputs (Level 3)
Derivative [Line Items]
Derivative liability, fair value	$ 0