COMMODITY DERIVATIVE INSTRUMENTS - Schedule of Derivative Instruments (Details) bbl in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) $ / bbl bbl	Dec. 31, 2018 USD ($) $ / bbl bbl
Derivative [Line Items]
Fair Value	$ (1,510,573)	$ 695,941
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Derivative [Line Items]
Weighted Average Strike Price (in usd per barrel) | $ / bbl	37.25	48.78
Remaining Volume (Barrels) | bbl	210	60
Fair Value	$ (1,456,700)	$ (1,048,400)
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Derivative [Line Items]
Weighted Average Strike Price (in usd per barrel) | $ / bbl	76.90	68.69
Remaining Volume (Barrels) | bbl	210	60
Fair Value	$ (153,636)	$ 1,097,124
Futures
Derivative [Line Items]
Weighted Average Strike Price (in usd per barrel) | $ / bbl	79.50	70.42
Remaining Volume (Barrels) | bbl	60	69
Fair Value	$ 99,763	$ 394,317
Futures
Derivative [Line Items]
Weighted Average Strike Price (in usd per barrel) | $ / bbl		45.41
Remaining Volume (Barrels) | bbl		30
Fair Value		$ 252,900