Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues
Oil, natural gas liquids and natural gas sales	$ 171,637	$ 219,290	$ 294,401	$ 407,112
Loss on derivative instruments, net	(65,872)	(50,964)	(60,417)	(16,928)
Total revenues	105,765	168,326	233,984	390,184
Operating Costs and Expenses
Oil, natural gas liquids and natural gas production	42,840	53,581	90,567	121,335
Production and ad valorem taxes	11,265	13,352	22,435	32,417
Depreciation, depletion and amortization	117,035	149,843	236,397	284,224
Asset impairment	0	60,413	220,025	66,996
Exploration	1,520	11,018	1,762	11,781
General and administrative (including non-cash stock based compensation of $5,504 and $6,027 for the three months ended June 30, 2016 and 2015, respectively, and $7,975 and $11,107 for the six months ended June 30, 2016 and 2015, respectively)	23,548	38,652	53,073	70,707
Accretion of discount on asset retirement obligations	1,779	1,669	3,536	3,679
(Gain) loss on sale of assets and other	(161,097)	1,476	(160,875)	(26,868)
Total operating costs and expenses	36,890	330,004	466,920	564,271
Operating Income (Loss)	68,875	(161,678)	(232,936)	(174,087)
Other Income (Expense)
Interest expense	(9,038)	(11,244)	(18,871)	(23,002)
Other income	63	41	159	87
Total other expense	(8,975)	(11,203)	(18,712)	(22,915)
Income (Loss) Before Income Taxes	59,900	(172,881)	(251,648)	(197,002)
Income tax expense (benefit)	23,141	(61,280)	(85,291)	(69,981)
Net Income (Loss)	$ 36,759	$ (111,601)	$ (166,357)	$ (127,021)
Diluted Earnings Per Average Common Share (in dollars per share)	$ 0.38	$ (1.52)	$ (1.81)	$ (1.74)
Basic Earnings Per Average Common Share (in dollars per share)	$ 0.38	$ (1.52)	$ (1.81)	$ (1.74)
Diluted Average Common Shares Outstanding (in shares)	97,389	73,452	91,850	73,143
Basic Average Common Shares Outstanding (in shares)	97,067	73,452	91,850	73,143
Dividends Per Common Share (in dollars per share)	$ 0	$ 0.02	$ 0	$ 0.04