SEGMENT INFORMATION - Selected Financial Information for Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 442,842	$ 147,416	$ 779,023	$ 371,704
Lease bonus - mineral acreage	0	4,062	0	4,062
Realized (loss) gain on derivatives	(42,611)	44,110	(68,524)	54,977
Unrealized (loss) gain on derivatives	(42,804)	(132,668)	(86,227)	3,762
Expenses	212,321	498,230	386,503	676,283
Operating (loss) income	145,106	(435,310)	237,769	(241,778)
Total assets	3,834,549	4,001,133	3,834,549	4,001,133	$ 3,687,280
Capital expenditures	115,903	195,959	260,674	474,554
Depletion, depreciation and amortization	91,444	93,350	166,307	184,057
Full-cost ceiling impairment	0	324,001	0	324,001
Corporate
Segment Reporting Information [Line Items]
Lease bonus - mineral acreage		0	0	0
Realized (loss) gain on derivatives	0	0	0	0
Unrealized (loss) gain on derivatives	0	0	0	0
Expenses	22,761	12,409	42,723	26,726
Operating (loss) income	(22,761)	(12,409)	(42,723)	(26,726)
Total assets	88,508	76,571	88,508	76,571
Capital expenditures	112	594	245	1,381
Depletion, depreciation and amortization	700	700	1,300	1,400
Consolidations and Eliminations
Segment Reporting Information [Line Items]
Lease bonus - mineral acreage		0	0	0
Realized (loss) gain on derivatives	0	0	0	0
Unrealized (loss) gain on derivatives	0	0	0	0
Expenses	(39,841)	(21,566)	(68,312)	(43,485)
Operating (loss) income	0	0	0	0
Total assets	0	0	0	0
Capital expenditures	0	0	0	0
Exploration and Production | Operating Segments
Segment Reporting Information [Line Items]
Lease bonus - mineral acreage		4,062	0	4,062
Realized (loss) gain on derivatives	(42,611)	44,110	(68,524)	54,977
Unrealized (loss) gain on derivatives	(42,804)	(132,668)	(86,227)	3,762
Expenses	199,127	483,812	355,571	645,137
Operating (loss) income	130,712	(441,723)	222,040	(255,361)
Total assets	2,942,429	3,159,528	2,942,429	3,159,528
Capital expenditures	107,928	130,709	242,793	340,444
Depletion, depreciation and amortization	83,000	87,800	149,400	172,900
Capital expenditures attributable to land and seismic acquisition expenditures	6,900	9,600	15,600	49,300
Midstream | Operating Segments
Segment Reporting Information [Line Items]
Lease bonus - mineral acreage		0	0	0
Realized (loss) gain on derivatives	0	0	0	0
Unrealized (loss) gain on derivatives	0	0	0	0
Expenses	30,274	23,575	56,521	47,905
Operating (loss) income	37,155	18,822	58,452	40,309
Total assets	803,612	765,034	803,612	765,034
Capital expenditures	7,863	64,656	17,636	132,729
Depletion, depreciation and amortization	7,800	5,000	15,600	9,800
Net income attributable to non-controlling interest in subsidiaries		(7,500)	(24,800)	(16,800)
Capital expenditures attributable to non-controlling interest	3,800	31,900	8,200	79,400
Operating Income (Loss) | Midstream | Operating Segments
Segment Reporting Information [Line Items]
Net income attributable to non-controlling interest in subsidiaries	(15,900)
Oil and natural gas revenues
Segment Reporting Information [Line Items]
Revenues	412,074	118,767	728,307	316,681
Oil and natural gas revenues | Corporate
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Oil and natural gas revenues | Consolidations and Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Oil and natural gas revenues | Exploration and Production | Operating Segments
Segment Reporting Information [Line Items]
Revenues	411,134	118,258	725,780	315,053
Oil and natural gas revenues | Midstream | Operating Segments
Segment Reporting Information [Line Items]
Revenues	940	509	2,527	1,628
Midstream services revenues
Segment Reporting Information [Line Items]
Revenues	19,850	14,668	35,288	30,498
Midstream services revenues | Corporate
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Midstream services revenues | Consolidations and Eliminations
Segment Reporting Information [Line Items]
Revenues	(39,841)	(21,566)	(68,312)	(43,485)
Midstream services revenues | Exploration and Production | Operating Segments
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Midstream services revenues | Midstream | Operating Segments
Segment Reporting Information [Line Items]
Revenues	59,691	36,234	103,600	73,983
Sales of purchased natural gas
Segment Reporting Information [Line Items]
Revenues	10,918	13,981	15,428	24,525
Sales of purchased natural gas | Corporate
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Sales of purchased natural gas | Consolidations and Eliminations
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Sales of purchased natural gas | Exploration and Production | Operating Segments
Segment Reporting Information [Line Items]
Revenues	4,120	8,327	6,582	11,922
Sales of purchased natural gas | Midstream | Operating Segments
Segment Reporting Information [Line Items]
Revenues	$ 6,798	$ 5,654	$ 8,846	$ 12,603