Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Oil, natural gas liquids and natural gas sales	$ 357,866	$ 176,375
Gain (loss) on derivative instruments, net	(1,695)	64,546
Total revenues	356,171	240,921
Operating Costs and Expenses
Oil, natural gas liquids and natural gas production	52,635	41,288
Production and ad valorem taxes	22,568	12,820
Depreciation, depletion and amortization	124,210	99,652
Asset impairment	177	1,460
Exploration	1,398	3,636
General and administrative (including stock-based compensation of $4,145 and $3,197 for the three months ended March 31, 2018 and 2017, respectively)	22,257	20,516
Accretion of discount on asset retirement obligations	1,533	1,414
Gain on sale of assets and other, net	(33,723)	(1,175)
Total operating costs and expenses	191,055	179,611
Operating Income	165,116	61,310
Other Income (Expense)
Interest expense	(10,248)	(9,023)
Other income	227	557
Total other expense	(10,021)	(8,466)
Income Before Income Taxes	155,095	52,844
Income tax expense	36,180	19,441
Net Income	$ 118,915	$ 33,403
Diluted Earnings Per Average Common Share (in dollars per share)	$ 1.22	$ 0.34
Basic Earnings Per Average Common Share (in dollars per share)	$ 1.22	$ 0.34
Diluted Average Common Shares Outstanding (in shares)	97,818	97,607
Basic Average Common Shares Outstanding (in shares)	97,321	97,140