SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Standardized Measure of Discounted Future Net Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Roll Forward]
Beginning of Period	$ 1,879,643	$ 753,986	$ 379,026
Sales of Oil and Natural Gas Produced, Net of Production Costs	(424,548)	(381,961)	(153,626)
Extensions and Discoveries	282,528	549,353	217,146
Previously Estimated Development Cost Incurred During the Period	100,987	115,542	46,834
Net Change of Prices and Production Costs	(680,119)	484,122	216,217
Change in Future Development Costs	(174,729)	(91,829)	(34,753)
Revisions of Quantity and Timing Estimates	(226,721)	66,185	28,915
Accretion of Discount	218,023	75,800	37,942
Change in Income Taxes	156,621	(296,571)	(3,617)
Purchases of Minerals in Place	338,289	502,193	0
Other	208,087	102,823	19,902
End of Period	$ 1,678,061	$ 1,879,643	$ 753,986