SUPPLEMENTAL OIL AND GAS INFORMATION (UNAUDITED) - Change In Standardized Measure (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Standardized Measure of Discounted Future Net Cash Flows Relating to Proved Oil and Gas Reserves [Roll Forward]
Beginning balance	$ 5,861,117	$ 6,483,308	$ 5,010,446
Discoveries and extensions, net of related future costs	311,336	1,075,839	1,280,499
Net changes in prices and production costs	(4,326,254)	(1,510,104)	2,078,479
Accretion of discount	750,041	813,480	596,569
Revisions of previous quantity estimates	(107,467)	28,310	586,494
Timing and other	5,992	(192,563)	(76,761)
Development costs incurred	501,093	468,748	338,297
Sales and transfers, net of production costs	(746,310)	(1,316,752)	(1,343,872)
Sales of reserves in place	0	(1,350)	(1,290,594)
Net change in income taxes	812,607	12,201	(696,249)
Ending balance	$ 3,062,155	$ 5,861,117	$ 6,483,308