Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues
Oil, natural gas liquids and natural gas sales	$ 371,567	$ 218,723	$ 729,433	$ 395,098
Gain (loss) on derivative instruments, net	(31,919)	38,101	(33,614)	102,647
Total revenues	339,648	256,824	695,819	497,745
Operating Costs and Expenses
Oil, natural gas liquids and natural gas production	57,958	43,909	110,593	85,197
Production and ad valorem taxes	24,733	13,218	47,301	26,038
Depreciation, depletion and amortization	134,011	121,549	258,221	221,201
Asset impairment	73	29	250	1,489
Exploration	1,059	1,998	2,457	5,634
General and administrative (including stock-based compensation of $4,618 and $3,191 for the three months ended June 30, 2018 and 2017, respectively, and $8,763 and $6,388 for the six months ended June 30, 2018 and 2017, respectively)	21,933	19,908	44,190	40,424
Accretion of discount on asset retirement obligations	1,567	1,443	3,100	2,857
(Gain) loss on sale of assets and other, net	(113)	172	(33,836)	(1,003)
Total operating costs and expenses	241,221	202,226	432,276	381,837
Operating Income	98,427	54,598	263,543	115,908
Other Income (Expense)
Interest expense	(10,803)	(9,202)	(21,051)	(18,225)
Other income	465	218	692	775
Total other expense	(10,338)	(8,984)	(20,359)	(17,450)
Income Before Income Taxes	88,089	45,614	243,184	98,458
Income tax expense	19,815	16,133	55,995	35,574
Net Income	$ 68,274	$ 29,481	$ 187,189	$ 62,884
Diluted Earnings Per Average Common Share (in dollars per share)	$ 0.70	$ 0.30	$ 1.91	$ 0.64
Basic Earnings Per Average Common Share (in dollars per share)	$ 0.70	$ 0.30	$ 1.92	$ 0.65
Diluted Average Common Shares Outstanding (in shares)	98,080	97,693	97,942	97,648
Basic Average Common Shares Outstanding (in shares)	97,433	97,189	97,377	97,165