Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 2,939	$ 1,521
Trade accounts receivable - net	68,748	67,991
Fair value of commodity derivative instruments	972	3,302
Deferred tax asset	4,414	3,322
Prepaid expenses	14,454	9,873
Total current assets	91,527	86,009
Property and equipment, at cost under the successful efforts method of accounting	2,299,323	2,025,647
Less accumulated depreciation, depletion, amortization and impairments	(569,124)	(427,580)
Net property and equipment	1,730,199	1,598,067
Restricted cash	6,023	6,023
Fair value of commodity derivative instruments	675	211
Deferred financing costs -- net of accumulated amortization of $4,800 at September 30, 2013 and $2,596 at December 31, 2012	10,851	12,386
Other assets	4,023	2,931
Total Assets	1,843,298	1,705,627
Current liabilities:
Accounts payable	55,410	34,772
Accrued expenses	103,160	117,372
Asset retirement obligations	47,482	30,179
Fair value of commodity derivative instruments	10,694	10,026
Total current liabilities	216,746	192,349
Long-term debt	621,723	689,911
Asset retirement obligations	240,288	204,931
Deferred tax liabilities	124,025	67,694
Fair value of commodity derivative instruments	281	3,637
Other	1,158	1,132
Total Liabilities	1,204,221	1,159,654
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.001 par value. Authorized 1,000,000 shares; no shares issued and outstanding at September 30, 2013 and December 31, 2012	0	0
Common stock, par value $0.001 per share. Authorized 75,000,000 shares; shares issued: 40,948,737 and 40,601,887 at September 30, 2013 and December 31, 2012, respectively; shares outstanding: 39,083,424 and 39,103,203 at September 30, 2013 and December 31, 2012, respectively	40	40
Additional paid-in capital	516,690	510,469
Treasury stock, at cost, 1,865,313 and 1,498,684 shares at September 30, 2013 and December 31, 2012, respectively	(30,926)	(20,477)
Retained earnings	153,273	55,941
Total stockholders' equity	639,077	545,973
Total liabilities and stockholders' equity	$ 1,843,298	$ 1,705,627