CONSOLIDATED STATEMENT OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating revenue:
Oil production									$ 416,497	$ 516,104	$ 715,104
Natural gas production									83,509	166,494	190,580
Natural gas liquids production									32,322	85,642	60,687
Other operational income									4,369	7,951	7,808
Derivative income, net									7,952	19,351	0
Total operating revenue	$ 110,499	$ 132,196	$ 149,525	$ 153,498	$ 184,780	$ 183,213	$ 207,046	$ 223,830	544,649	795,542	974,179
Operating expenses:
Lease operating expenses									100,139	176,495	201,153
Transportation, processing and gathering expenses									58,847	64,951	42,172
Production taxes									6,877	12,151	15,029
Depreciation, depletion and amortization									281,688	340,006	350,574
Write-down of oil and gas properties	351,062	295,679	224,294	491,412	304,062	47,130	0	0	1,362,447	351,192	0
Accretion expense									25,988	28,411	33,575
Salaries, general and administrative expenses									69,384	66,451	59,524
Franchise tax settlement									0	0	12,590
Incentive compensation expense									2,242	10,361	15,340
Other operational expenses									2,360	862	151
Derivative expense, net									0	0	2,090
Total operating expenses									1,909,972	1,050,880	732,198
Income (loss) from operations	(342,759)	(297,209)	(228,161)	(497,194)	(286,147)	(34,356)	16,613	48,552	(1,365,323)	(255,338)	241,981
Other (income) expenses:
Interest expense									43,928	38,855	32,837
Interest income									(580)	(574)	(1,695)
Other income									(1,783)	(2,332)	(2,799)
Other expense									434	274	0
Loss on early extinguishment of debt									0	0	27,279
Total other expenses									41,999	36,223	55,622
Income (loss) before income taxes									(1,407,322)	(291,561)	186,359
Provision (benefit) for income taxes:
Current									(44,096)	159	(10,904)
Deferred									(272,311)	(102,177)	79,629
Total income taxes									(316,407)	(102,018)	68,725
Net income (loss)	$ (318,656)	$ (291,965)	$ (152,906)	$ (327,388)	$ (190,515)	$ (29,415)	$ 4,444	$ 25,943	$ (1,090,915)	$ (189,543)	$ 117,634
Basic earnings (loss) per share (in usd per share)	$ (5.76)	$ (5.28)	$ (2.77)	$ (5.93)	$ (3.47)	$ (0.54)	$ 0.08	$ 0.52	$ (19.75)	$ (3.60)	$ 2.36
Diluted earnings (loss) per share (in usd per share)	$ (5.76)	$ (5.28)	$ (2.77)	$ (5.93)	$ (3.47)	$ (0.54)	$ 0.08	$ 0.52	$ (19.75)	$ (3.60)	$ 2.36
Average shares outstanding (in shares)									55,250	52,721	48,693
Average shares outstanding assuming dilution (in shares)									55,250	52,721	48,735