XML 55 R36.htm IDEA: XBRL DOCUMENT v3.8.0.1
Organization and Significant Accounting Policies (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
region
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Nature of operations [Abstract]      
Number of operating regions in domicile country | region 3    
Accounts Receivable [Abstract]      
Allowance for doubtful accounts $ 364 $ 228  
Oil and gas properties, full cost method of accounting:      
Discount rate used in future net cash flows relating to proved oil and gas reserves (in hundredths) 10.00%    
Proved property impairment $ 0 67,626 $ 128,573
Share-Based Payments [Abstract]      
Stock-based compensation expense 3,238 3,194 3,912
Entity's asset retirement obligation transactions [Roll Forward]      
Beginning asset retirement obligation 8,623 9,679  
New wells placed on production and other 1,088 119  
Property acquisitions and dispositions, net (1,551) (1,832)  
Accretion expense (451) (491) (565)
Revisions 164 166  
Ending asset retirement obligation $ 8,775 $ 8,623 $ 9,679
Revenue Recognition and Major Purchasers [Abstract]      
Entity wide revenue, major customers (in hundredths) 69.00% 71.00% 54.00%
Entity wide revenue, number of major purchasers of oil and gas 3 2 1
Income Taxes [Abstract]      
Valuation allowance for deferred tax assets $ 80,445 $ 137,754 $ 103,682