Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues
Oil and natural gas revenues	$ 155,998	$ 67,000	$ 34,042
Realized gain on derivatives	13,960	7,106	5,299
Unrealized (loss) gain on derivatives	(4,802)	5,138	3,139
Total revenues	165,156	79,244	42,480
Expenses
Production taxes and marketing	11,672	6,278	1,982
Lease operating	28,184	7,244	5,284
Depletion, depreciation and amortization	80,454	31,754	15,596
Accretion of asset retirement obligations	256	209	155
Full-cost ceiling impairment	63,475	35,673	0
General and administrative	14,543	13,394	9,702
Total expenses	198,584	94,552	32,719
Operating (loss) income	(33,428)	(15,308)	9,761
Other income (expense)
Net loss on asset sales and inventory impairment	(485)	(154)	(224)
Interest expense	(1,002)	(683)	(3)
Interest and other income	224	315	364
Total other (expense) income	(1,263)	(522)	137
(Loss) income before income taxes	(34,691)	(15,830)	9,898
Income tax (benefit) provision
Current		(46)	(1,411)
Deferred	(1,430)	(5,475)	4,932
Total income tax (benefit) provision	(1,430)	(5,521)	3,521
Net (loss) income	$ (33,261)	$ (10,309)	$ 6,377
Basic
Basic	53,957	42,718	41,038
Diluted
Diluted	53,957	42,718	41,134
Class A
Basic
Basic	$ (0.62)	$ (0.25)	$ 0.15
Diluted
Diluted	$ (0.62)	$ (0.25)	$ 0.15
Basic
Basic	53,852	41,687	40,007
Diluted
Diluted	53,852	41,687	40,103
Class B
Basic
Basic	$ (0.35)	$ 0.02	$ 0.42
Diluted
Diluted	$ (0.35)	$ 0.02	$ 0.42
Basic
Basic	105	1,031	1,031
Diluted
Diluted	105	1,031	1,031