Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 1,521	$ 80,128
Trade accounts receivable - net	67,991	31,817
Fair value of commodity derivative instruments	3,302	587
Deferred tax asset	3,322
Prepaid expenses	9,873	11,046
Total current assets	86,009	123,578
Property and equipment, at cost under the successful efforts method of accounting	2,025,647	1,082,248
Less accumulated depreciation, depletion, amortization and impairments	(427,580)	(305,110)
Net property and equipment	1,598,067	777,138
Restricted cash	6,023	6,023
Fair value of commodity derivative instruments	211
Deferred financing costs -- net of accumulated amortization of $2,596 and $1,061 at December 31, 2012 and 2011, respectively	12,386	5,452
Other assets	2,931	3,029
Total Assets	1,705,627	915,220
Current liabilities:
Accounts payable	34,772	25,393
Accrued expenses	117,372	58,538
Asset retirement obligations	30,179	25,578
Fair value of commodity derivative instruments	10,026	1,056
Deferred tax liabilities		2,823
Total current liabilities	192,349	113,388
Long-term debt	689,911	204,390
Asset retirement obligations	204,931	73,769
Deferred tax liabilities	67,694	31,775
Fair value of commodity derivative instruments	3,637	190
Other	1,132	663
Total Liabilities	1,159,654	424,175
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.001 par value. Authorized 1,000,000 shares; no shares issued and outstanding at December 31, 2012 and 2011, respectively
Common stock, par value $0.001 per share. Authorized 75,000,000 shares; shares issued: 40,601,887 and 40,326,451 at December 31, 2012 and 2011, respectively; shares outstanding: 39,103,203 and 39,404,106 December 31, 2012 and 2011, respectively	40	40
Additional paid-in capital	510,469	505,235
Treasury stock, at cost, 1,498,684 and 922,345 shares at December 31, 2012 and 2011, respectively	(20,477)	(11,361)
Retained earnings (accumulated deficit)	55,941	(2,869)
Total stockholders' equity	545,973	491,045
Total liabilities and stockholders' equity	$ 1,705,627	$ 915,220