Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 8,812	$ 1,521
Trade accounts receivable - net	70,707	67,991
Fair value of commodity derivative instruments	501	3,302
Deferred tax asset	8,949	3,322
Prepaid expenses	6,868	9,873
Total current assets	95,837	86,009
Property and equipment, at cost under the successful efforts method of accounting	2,355,219	2,025,647
Less accumulated depreciation, depletion, amortization and impairments	(618,788)	(427,580)
Net property and equipment	1,736,431	1,598,067
Deposit for Nexen Acquisition	7,040
Restricted cash	6,023	6,023
Fair value of commodity derivative instruments	238	211
Deferred financing costs -- net of accumulated amortization of $5,549 and $2,596 at December 31, 2013 and 2012, respectively	10,106	12,386
Other assets	2,156	2,931
Total Assets	1,857,831	1,705,627
Current liabilities:
Accounts payable	59,431	34,772
Accrued expenses	131,125	117,372
Asset retirement obligations	51,601	30,179
Fair value of commodity derivative instruments	29,636	10,026
Total current liabilities	271,793	192,349
Long-term debt	627,355	689,911
Asset retirement obligations	203,849	204,931
Deferred tax liabilities	122,812	67,694
Fair value of commodity derivative instruments	2,136	3,637
Other	673	1,132
Total Liabilities	1,228,618	1,159,654
Commitments and contingencies (Note 13)
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: 40,970,137 and 40,601,887 at December 31, 2013 and 2012, respectively; shares outstanding: 39,097,394 and 39,103,203 December 31, 2012 and 2011, respectively	41	40
Additional paid-in capital	519,114	510,469
Treasury stock, at cost, 1,498,684 and 922,345 shares at December 31, 2012 and 2011, respectively	(31,157)	(20,477)
Retained earnings	141,215	55,941
Total stockholders' equity	629,213	545,973
Total liabilities and stockholders' equity	$ 1,857,831	$ 1,705,627