Consolidated statements of cash flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ (342,459,000)	$ 324,595,000	$ 548,974,000
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Non-cash stock-based compensation, net	8,290,000	36,396,000	35,734,000
Depletion, depreciation and amortization	265,746,000	212,677,000	158,389,000
Impairment expense	620,889,000	0	0
Mark-to-market on derivatives:
Gain on derivatives, net	(79,151,000)	(42,984,000)	(350,000)
Settlements received for matured commodity derivatives, net	63,221,000	6,090,000	37,583,000
Settlements (paid) received for early terminations of commodity derivatives, net	(5,409,000)	0	4,234,000
Premiums paid for commodity derivatives	(9,063,000)	(20,335,000)	(25,853,000)
Amortization of debt issuance costs	3,341,000	3,331,000	4,086,000
Amortization of operating lease right-of-use assets	14,563,000	0	0
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
Deferred income tax (benefit) expense	(2,588,000)	5,056,000	0
Other, net	3,887,000	12,551,000	(2,024,000)
Decrease (increase) in accounts receivable, net	8,924,000	4,669,000	(12,124,000)
Increase in other current assets	(14,059,000)	(1,865,000)	(3,461,000)
Decrease (increase) in other noncurrent assets, net	2,327,000	124,000	(4,774,000)
(Decrease) increase in accounts payable and accrued liabilities	(28,983,000)	11,163,000	9,137,000
(Decrease) increase in undistributed revenue and royalties	(16,037,000)	10,989,000	11,014,000
Decrease in other current liabilities	(13,968,000)	(23,799,000)	(2,327,000)
(Decrease) increase in other noncurrent liabilities	(4,397,000)	(854,000)	8,821,000
Net cash provided by operating activities	475,074,000	537,804,000	384,914,000
Cash flows from investing activities:
Deposit utilized for sale of oil and natural gas properties	0	0	(3,000,000)
Acquisitions of oil and natural gas properties, net of closing adjustments	(199,284,000)	(17,538,000)	0
Capital expenditures:
Oil and natural gas properties	(458,985,000)	(673,584,000)	(538,122,000)
Midstream service assets	(7,910,000)	(6,784,000)	(20,887,000)
Other fixed assets	(2,433,000)	(7,308,000)	(4,905,000)
Investment in equity method investee (see Note 4.d)	0	0	(31,808,000)
Proceeds from disposition of equity method investee, net of selling costs (see Note 4.d)	0	1,655,000	829,615,000
Proceeds from dispositions of capital assets, net of selling costs	6,901,000	12,603,000	64,157,000
Net cash provided by (used in) investing activities	(661,711,000)	(690,956,000)	295,050,000
Cash flows from financing activities:
Borrowings on Senior Secured Credit Facility	275,000,000	210,000,000	190,000,000
Payments on Senior Secured Credit Facility	(90,000,000)	(20,000,000)	(260,000,000)
Early redemption of debt	0	0	(518,480,000)
Share repurchases	0	(97,055,000)	0
Stock exchanged for tax withholding	(2,657,000)	(4,418,000)	(7,662,000)
Proceeds from exercise of stock options	0	86,000	397,000
Payments for debt issuance costs	0	(2,469,000)	(4,732,000)
Net cash provided by (used in) financing activities	182,343,000	86,144,000	(600,477,000)
Net increase (decrease) in cash and cash equivalents	(4,294,000)	(67,008,000)	79,487,000
Cash and cash equivalents, beginning of period	45,151,000	112,159,000	32,672,000
Cash and cash equivalents, end of period	$ 40,857,000	$ 45,151,000	$ 112,159,000