Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Crude oil, natural gas and NGLs sales	$ 307,409	$ 372,439	$ 967,464	$ 1,003,597
Commodity price risk management gain (loss), net	54,867	(94,394)	(87,858)	(257,760)
Other income	3,667	2,672	11,495	8,011
Total revenues	365,943	280,717	891,101	753,848
Costs, expenses and other:
Lease operating expenses	36,498	33,046	106,047	94,942
Production taxes	13,039	23,984	57,849	66,757
Transportation, gathering and processing expenses	10,999	9,234	34,631	25,511
Exploration, geologic and geophysical expense	209	1,032	3,492	4,553
Impairment of properties and equipment	167	1,488	37,021	194,230
General and administrative expense	41,091	48,240	123,497	121,183
Depreciation, depletion and amortization	171,839	147,540	491,784	409,952
Accretion of asset retirement obligations	1,356	1,200	4,503	3,773
Loss on sale of properties and equipment	43,872	2,118	9,599	3,199
Other expenses	2,492	2,711	8,882	8,187
Total cost, expenses and other	321,562	270,593	877,305	932,287
Income (loss) from operations	44,381	10,124	13,796	(178,439)
Interest expense	(17,859)	(17,622)	(53,742)	(52,561)
Interest income	48	188	63	405
Income (loss) before income taxes	26,570	(7,310)	(39,883)	(230,595)
Income tax (expense) benefit	(10,662)	3,876	4,163	53,765
Net income (loss)	$ 15,908	$ (3,434)	$ (35,720)	$ (176,830)
Earnings per share:
Basic	$ 0.25	$ (0.05)	$ (0.55)	$ (2.68)
Diluted	$ 0.25	$ (0.05)	$ (0.55)	$ (2.68)
Weighted-average common shares outstanding
Basic	62,547	66,073	64,835	66,032
Diluted	62,595	66,073	64,835	66,032