CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Oil, natural gas liquids and natural gas sales	$ 763,261	$ 1,344,194	$ 1,256,317
Gain (loss) on derivative instruments, net	115,293	335,019	(50,024)
Total revenues	878,554	1,679,213	1,206,293
Operating Costs and Expenses
Oil, natural gas liquids and natural gas production	228,380	274,432	257,438
Production and ad valorem taxes	57,380	102,063	94,103
Depreciation, depletion and amortization	593,789	548,564	452,876
Asset impairment	1,292,308	416,801	13,906
Exploration	14,878	28,090	14,036
General and administrative	149,132	122,052	113,821
Accretion of discount on asset retirement obligations	7,108	7,608	6,995
(Gain) loss on sale of assets and other, net	(26,570)	2,642	981
Total operating costs and expenses	2,316,405	1,502,252	954,156
Operating Income (Loss)	(1,437,851)	176,961	252,137
Other Income (Expense)
Interest expense	(43,108)	(37,771)	(39,736)
Other income	223	1,181	3,803
Total other expense	(42,885)	(36,590)	(35,933)
Income (Loss) From Continuing Operations Before Income Taxes	(1,480,736)	140,371	216,204
Income tax expense (benefit)	(535,005)	40,728	74,323
Income (Loss) From Continuing Operations	(945,731)	99,643	141,881
Discontinued Operations, net of tax
Income from discontinued operations	0	29,292	59,079
Gain on disposal of discontinued operations, net	0	439,097	3,594
Income From Discontinued Operations	0	468,389	62,673
Net Income (Loss)	$ (945,731)	$ 568,032	$ 204,554
Diluted Earnings Per Average Common Share
Continuing operations (in dollars per share)	$ (12.43)	$ 1.36	$ 1.96
Discontinued operations (in dollars per share)	0.00	6.39	0.86
Net Income (Loss) (in dollars per share)	(12.43)	7.75	2.82
Basic Earnings Per Average Common Share
Continuing operations (in dollars per share)	(12.43)	1.37	1.96
Discontinued operations (in dollars per share)	0.00	6.42	0.87
Net Income (Loss) (in dollars per share)	$ (12.43)	$ 7.79	$ 2.83
Diluted Average Common Shares Outstanding (in shares)	76,078,371	73,274,631	72,470,622
Basic Average Common Shares Outstanding (in shares)	76,078,371	72,896,579	72,317,865