Consolidated statements of operations - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Total revenues	$ 837,281,000	$ 1,105,775,000	$ 822,162,000
Costs and expenses:
Lease operating expenses	90,786,000	91,289,000	75,049,000
Production and ad valorem taxes	40,712,000	49,457,000	37,802,000
General and administrative	54,729,000	96,138,000	96,312,000
Organizational restructuring expenses	16,371,000	0	0
Depletion, depreciation and amortization	265,746,000	212,677,000	158,389,000
Impairment expense	620,889,000	0	0
Other operating expenses	4,118,000	4,472,000	4,931,000
Total costs and expenses	1,245,872,000	757,283,000	572,490,000
Operating income (loss)	(408,591,000)	348,492,000	249,672,000
Non-operating income (expense):
Gain on derivatives, net	79,151,000	42,984,000	350,000
Interest expense	(61,547,000)	(57,904,000)	(89,377,000)
Litigation settlement	42,500,000	0	0
Income from equity method investee (see Note 4.d)	0	0	8,485,000
Gain on sale of investment in equity method investee (see Note 4.d)	0	0	405,906,000
Loss on early redemption of debt	0	0	(23,761,000)
Loss on disposal of assets, net	(248,000)	(5,798,000)	(1,306,000)
Write-off of debt issuance costs	(935,000)	0	0
Other income, net	4,623,000	1,070,000	805,000
Total non-operating income (expense), net	63,544,000	(19,648,000)	301,102,000
Income (loss) before income taxes	(345,047,000)	328,844,000	550,774,000
Income tax benefit (expense):
Current	0	807,000	(1,800,000)
Deferred	2,588,000	(5,056,000)	0
Total income tax benefit (expense)	2,588,000	(4,249,000)	(1,800,000)
Net income (loss)	$ (342,459,000)	$ 324,595,000	$ 548,974,000
Net income (loss) per common share:
Basic (in dollars per share)	$ (1.48)	$ 1.40	$ 2.30
Diluted (in dollars per share)	$ (1.48)	$ 1.39	$ 2.29
Weighted-average common shares outstanding:
Basic (in shares)	231,295	232,339	239,096
Diluted (in shares)	231,295	233,172	240,122
Oil sales
Revenues:
Total revenues	$ 572,918,000	$ 605,197,000	$ 445,012,000
NGL sales
Revenues:
Total revenues	100,330,000	149,843,000	101,438,000
Natural gas sales
Revenues:
Total revenues	33,300,000	53,490,000	75,057,000
Midstream service revenues
Revenues:
Total revenues	11,928,000	8,987,000	10,517,000
Costs and expenses:
Costs of goods and services sold	4,486,000	2,872,000	4,099,000
Transportation and marketing expenses
Costs and expenses:
Costs of goods and services sold	25,397,000	11,704,000	0
Sales of purchased oil
Revenues:
Total revenues	118,805,000	288,258,000	190,138,000
Costs and expenses:
Costs of goods and services sold	$ 122,638,000	$ 288,674,000	$ 195,908,000