Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Crude oil, natural gas, and NGLs sales	$ 305,225	$ 189,692
Commodity price risk management gain (loss), net	(47,240)	80,704
Other income	2,615	3,311
Total revenues	260,600	273,707
Costs, expenses and other:
Lease operating expenses	29,636	19,789
Production taxes	20,169	12,399
Transportation, gathering, and processing expenses	7,313	5,902
Exploration, geologic, and geophysical expense	2,646	954
Impairment of properties and equipment	33,188	2,193
General and administrative expense	35,696	26,315
Depreciation, depletion, and amortization	126,788	109,316
Accretion of asset retirement obligations	1,288	1,768
(Gain) loss on sale of properties and equipment	1,432	(160)
Other expenses	2,768	3,528
Total cost, expenses and other	260,924	182,004
Income (loss) from operations	(324)	91,703
Interest expense	(17,529)	(19,467)
Interest income	148	240
Income (loss) before income taxes	(17,705)	72,476
Income tax (expense) benefit	4,566	(26,330)
Net income (loss)	$ (13,139)	$ 46,146
Earnings per share:
Basic	$ (0.20)	$ 0.70
Diluted	$ (0.20)	$ 0.70
Weighted-average common shares outstanding
Basic	65,957	65,749
Diluted	65,957	66,117