Quarterly report pursuant to Section 13 or 15(d)

Long-term Debt (Details Textual)

v3.21.2
Long-term Debt (Details Textual)
3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2021
USD ($)
Jun. 30, 2020
USD ($)
Jun. 30, 2021
USD ($)
Jun. 30, 2020
USD ($)
Dec. 31, 2020
USD ($)
May 19, 2021
USD ($)
Oct. 18, 2018
USD ($)
Current portion of long-term debt $ 36,771,000   $ 36,771,000        
Repayments of outstanding balance     80,000,000 $ 50,000,000      
Gain (Loss) on Extinguishment of Debt, Total 0 $ 28,968,000 0 $ 47,469,000      
Term Loan [Member]              
Current portion of long-term debt 36,800,000   36,800,000        
Debt Instrument, Face Amount           $ 215,000,000.0  
Debt Instrument, Interest Rate, Stated Percentage           7.00%  
Credit Agreement [Member]              
Repayments of outstanding balance     48,000,000.0        
Borrowings outstanding 0   0   $ 80,000,000.0    
Line of Credit Facility, Maximum Borrowing Capacity 190,000,000.0   $ 190,000,000.0        
Credit Agreement, Maximum Leverage Ratio     3.00        
Credit Agreement, Leverage Ratio     2.00        
Credit Agreement, Minimum Current Ratio     1.00        
Credit Agreement, Minimum Percentage of Total Proved Reserves     90.00%        
Letters of Credit Outstanding, Amount 4,400,000   $ 4,400,000   4,400,000    
Line of Credit Facility, Interest Rate During Period     3.20%        
Credit Agreement [Member] | Letter of Credit [Member]              
Line of Credit Facility, Maximum Borrowing Capacity 30,000,000.0   $ 30,000,000.0        
Senior Second Lien Notes Due November 2023 [Member]              
Debt Instrument, Face Amount $ 552,500,000   $ 552,500,000   552,500,000   $ 625,000,000.0
Debt Instrument, Interest Rate, Stated Percentage             9.75%
Debt Instrument, Interest Rate, Effective Percentage             10.30%
Extinguishment of Debt, Amount         72,500,000    
Repayments of Long-term Debt, Total         23,900,000    
Gain (Loss) on Extinguishment of Debt, Total         47,500,000    
Write off of Deferred Debt Issuance Cost         $ 1,100,000