Quarterly report pursuant to Section 13 or 15(d)

Note 2 - Long-term Debt (Details Textual)

v3.21.1
Note 2 - Long-term Debt (Details Textual)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2021
USD ($)
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Oct. 18, 2018
USD ($)
Gain (Loss) on Extinguishment of Debt, Total $ (0) $ 18,501    
Credit Agreement [Member]        
Line of Credit Facility, Maximum Borrowing Capacity $ 190,000      
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   $ 4,400  
Line of Credit Facility, Interest Rate During Period 3.10%      
Credit Agreement [Member] | Line of Credit [Member]        
Line of Credit Facility, Maximum Borrowing Capacity $ 30,000      
Senior Second Lien Notes Due November 2023 [Member]        
Debt Instrument, Face Amount $ 552,460   552,460 $ 625,000
Debt Instrument, Interest Rate, Stated Percentage       9.75%
Debt Instrument, Interest Rate, Effective Percentage       9.20%
Extinguishment of Debt, Amount     72,500  
Repayments of Long-term Debt, Total     23,900  
Gain (Loss) on Extinguishment of Debt, Total     47,500  
Write off of Deferred Debt Issuance Cost     $ 1,100