Quarterly report pursuant to Section 13 or 15(d)

Accounting Policies (Narrative I) (Detail)

v3.3.0.814
Accounting Policies (Narrative I) (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Dec. 31, 2014
Error Corrections and Prior Period Adjustments Restatement [Line Items]              
Impairment Of Oil And Gas Properties $ 18,000 $ 500   $ 0 $ 29,200 $ 0  
Asset Impairment Charges 17,988       29,208    
Impairment of Oil and Gas Properties, percent   9.00%         7.00%
Net Income Loss (33,668)     3,109 $ (77,877) 20,788  
Net Income Loss, percent         9.00%    
Depreciation Depletion And Amortization 8,259     $ 4,289 $ 23,493 $ 15,444  
Scenario, Adjustment Related to Prior Period [Member]              
Error Corrections and Prior Period Adjustments Restatement [Line Items]              
Impairment Of Oil And Gas Properties   $ 600 $ (3,100)       $ 7,000
Net Income Loss   100 (3,500)       7,000
Depreciation Depletion And Amortization   $ 500 $ 400        
Scenario, Adjustment [Member]              
Error Corrections and Prior Period Adjustments Restatement [Line Items]              
Impairment Of Oil And Gas Properties 4,500       $ 7,000    
Impairment of Oil and Gas Properties, percent         33.00%    
Net Income Loss $ 3,600            
Scenario, Actual [Member]              
Error Corrections and Prior Period Adjustments Restatement [Line Items]              
Impairment Of Oil And Gas Properties             $ 98,300
Net Income Loss         $ 77,600    
Net Income Loss, percent 11.00%