Quarterly report pursuant to Section 13 or 15(d)

Debt (Detail)

v3.4.0.3
Debt (Detail) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Dec. 31, 2015
Line Of Credit Facility [Line Items]      
Credit facility borrowing base $ 20,100    
Long term debt $ 15,000   $ 15,000
Average interest rate on bank debt 4.36% 4.32%  
Incurred interest expense $ 500 $ 500  
Capitalized interest expense   $ 200  
Maximum [Member]      
Line Of Credit Facility [Line Items]      
Ratio of net debt to EBITDAX 3.0    
Revolving Credit Facility [Member] | IFC Credit Facility [Member]      
Line Of Credit Facility [Line Items]      
Maximum borrowing capacity under loan agreement $ 65,000    
Senior Tranche [Member]      
Line Of Credit Facility [Line Items]      
Maximum borrowing capacity under loan agreement 50,000    
Decrease in debt instrument $ 6,250    
Debt instrument interest rate spread 3.75%    
Debt instrument, commitment fee 1.50%    
Subordinated Tranche [Member]      
Line Of Credit Facility [Line Items]      
Maximum borrowing capacity under loan agreement $ 15,000    
Decrease in debt instrument $ 1,880    
Debt instrument interest rate spread 5.75%    
Debt instrument, commitment fee 2.30%