v2.4.0.6
Income Taxes - Significant Components of Net Deferred Tax Assets and Liabilities (Detail) (USD $)
In Thousands, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Deferred tax assets:    
Net operating loss carryforwards $ 27,353 $ 31,052
Unrealized loss on commodity derivatives   504
Other 542 866
Total deferred tax assets 27,895 32,422
Deferred tax liabilities:    
Difference in depreciation, depletion and capitalization methods-oil and gas properties (76,170) (78,174)
Unrealized gain on commodity derivatives (849)  
Total deferred tax liabilities (77,019) (78,174)
Net deferred tax liability $ (49,124) $ (45,752)