Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenue:
Oil and natural gas	$ 183,114	$ 86,645	$ 547,099	$ 284,666
Other	878	23	3,329	68
Total Revenues	183,992	86,668	550,428	284,734
Costs and expenses:
Lease operating	42,291	24,995	126,663	62,067
Transportation	974	160	2,317	410
Exploration expenditures and dry hole costs	5,146	966	13,609	17,862
Impairments	12	498	2,183	6,206
Depreciation, depletion and amortization	53,989	27,106	153,847	78,932
Accretion of liability for asset retirement obligations	6,266	3,472	18,464	10,031
General and administrative	6,426	5,995	20,927	16,993
Taxes, other than on earnings	3,285	3,189	8,884	9,834
Gain on sale of assets	(1,745)		(28,601)
Other	26,534	998	33,077	4,616
Total costs and expenses	143,178	67,379	351,370	206,951
Income from operations	40,814	19,289	199,058	77,783
Other income (expense):
Interest income	64	40	91	128
Interest expense	(13,177)	(5,114)	(39,370)	(15,081)
Gain (loss) on derivative instruments	(30,012)	(22,108)	(7,033)	(11,865)
Total other income (expense)	(43,125)	(27,182)	(46,312)	(26,818)
Income (loss) before income taxes	(2,311)	(7,893)	152,746	50,965
Current income tax expense	(25)	126	(175)	(174)
Deferred income tax expense	1,052	5,520	(55,239)	(16,134)
Total provision for income taxes	1,027	5,646	(55,414)	(16,308)
Net income (loss)	$ (1,284)	$ (2,247)	$ 97,332	$ 34,657
Basic earnings (loss) per share	$ (0.03)	$ (0.06)	$ 2.48	$ 0.88
Diluted earnings (loss) per share	$ (0.03)	$ (0.06)	$ 2.45	$ 0.88
Weighted average common shares used in computing earnings per share:
Basic	38,589	38,743	38,760	38,926
Diluted	38,589	38,743	39,256	39,056