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
Revenues
Oil and natural gas revenues	$ 58,179	$ 36,078	$ 117,498	$ 65,242
Realized gain on derivatives	254	4,713	646	7,776
Unrealized loss on derivatives	7,526	15,114	2,701	11,844
Total revenues	65,959	55,905	120,845	84,862
Expenses
Production taxes and marketing	4,451	2,619	8,548	4,783
Lease operating	10,140	6,375	21,040	11,020
Depletion, depreciation and amortization	20,234	19,913	48,466	31,119
Accretion of asset retirement obligations	80	58	161	111
Full-cost ceiling impairment	0	33,205	21,229	33,205
General and administrative	4,149	4,093	8,751	7,882
Total expenses	39,054	66,263	108,195	88,120
Operating (loss) income	26,905	(10,358)	12,650	(3,258)
Other income (expense)
Net loss on asset sales and inventory impairment	(192)	(60)	(192)	(60)
Interest expense	(1,609)	(1)	(2,880)	(309)
Interest and other income	47	30	115	103
Total other expense	(1,754)	(31)	(2,957)	(266)
Income (loss) before income taxes	25,151	(10,389)	9,693	(3,524)
Income tax provision (benefit)
Current	32	0	78	0
Deferred	0	(3,713)	0	(649)
Total income tax provision (benefit)	32	(3,713)	78	(649)
Net income (loss)	$ 25,119	$ (6,676)	$ 9,615	$ (2,875)
Basic
Basic (shares)	55,839	55,271	55,729	52,644
Diluted
Diluted (shares)	55,937	55,271	55,819	52,644
Class A
Basic
Basic (usd per share)	$ 0.45	$ (0.12)	$ 0.17	$ (0.06)
Diluted
Diluted (usd per share)	$ 0.45	$ (0.12)	$ 0.17	$ (0.06)
Basic
Basic (shares)	55,839	55,271	55,729	52,434
Diluted
Diluted (shares)	55,937	55,271	55,819	52,434
Class B
Basic
Basic (usd per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.07
Diluted
Diluted (usd per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.07
Basic
Basic (shares)	0	0	0	210
Diluted
Diluted (shares)	0	0	0	210