Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenue:
Oil and natural gas	$ 183,001	$ 99,249	$ 363,985	$ 198,021
Other	1,086	21	2,451	45
Total Revenues	184,087	99,270	366,436	198,066
Costs and expenses:
Lease operating	42,793	18,661	84,372	37,072
Transportation	693	99	1,343	250
Exploration expenditures and dry hole costs	6,530	2,587	8,463	16,896
Impairments	2,129	3,394	2,171	5,708
Depreciation, depletion and amortization	53,336	27,918	99,858	51,826
Accretion of liability for asset retirement obligations	6,166	3,411	12,198	6,559
General and administrative	7,409	5,654	14,501	10,998
Taxes, other than on earnings	2,739	2,904	5,599	6,645
Gain on sale of assets	(26,856)		(26,856)
Other	3,596	3,443	6,543	3,618
Total costs and expenses	98,535	68,071	208,192	139,572
Income from operations	85,552	31,199	158,244	58,494
Other income (expense):
Interest income	17	50	27	88
Interest expense	(13,098)	(5,093)	(26,193)	(9,967)
Gain on derivative instruments	36,930	30,305	22,979	10,243
Total other income (expense)	23,849	25,262	(3,187)	364
Income before income taxes	109,401	56,461	155,057	58,858
Current income tax expense	(50)		(150)	(300)
Deferred income tax expense	(39,772)	(21,060)	(56,291)	(21,654)
Total provision for income taxes	(39,822)	(21,060)	(56,441)	(21,954)
Net income	$ 69,579	$ 35,401	$ 98,616	$ 36,904
Basic earnings per share	$ 1.77	$ 0.90	$ 2.51	$ 0.94
Diluted earnings per share	$ 1.75	$ 0.90	$ 2.48	$ 0.94
Weighted average common shares used in computing earnings per share:
Basic	38,871	38,914	38,847	39,018
Diluted	39,383	39,027	39,302	39,132