Annual report pursuant to Section 13 and 15(d)

LONG TERM DEBT - Narrative (Details)

v3.20.4
LONG TERM DEBT - Narrative (Details)
1 Months Ended 12 Months Ended
Nov. 22, 2019
Oct. 21, 2019
USD ($)
Jul. 01, 2019
USD ($)
May 15, 2018
USD ($)
Nov. 30, 2019
USD ($)
May 31, 2018
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Oct. 05, 2018
USD ($)
Debt Instrument [Line Items]                    
Long-term debt             $ 944,843,000 $ 1,118,161,000    
8.5% Second Lien Notes due 2023                    
Debt Instrument [Line Items]                    
Long-term debt   $ 200,000,000.0                
Notes exchanged   $ 70,800,000                
8.5% Second Lien Notes due 2023 | Second Lien Notes                    
Debt Instrument [Line Items]                    
Interest rate percentage       8.50%            
Junior subordinated notes                   $ 350,000,000.0
Principal repaid             116,500,000      
Long-term debt         $ 200,000,000.0          
Notes exchanged         $ 70,800,000          
Aggregate principal amount repurchased and retired             13,500,000      
Covenant compliance, percent of net cash proceeds of asset sales for debt prepayment       1            
Covenant compliance, threshold amount of casualty events and condemnations       $ 20,000,000.0            
Redemption price, percentage of principal amount redeemed           101.00%        
8.5% Second Lien Notes due 2023 | Second Lien Notes | Period One                    
Debt Instrument [Line Items]                    
Redemption price percentage       104.00%            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Period Two                    
Debt Instrument [Line Items]                    
Redemption price percentage       102.00%            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Period Three                    
Debt Instrument [Line Items]                    
Redemption price percentage       100.00%            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio below 2.50 to 1.00                    
Debt Instrument [Line Items]                    
Debt to EBITDAX ratio       2.50            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio between 2.50 to 1.00 and 2.75 to 1.00                    
Debt Instrument [Line Items]                    
Increase in interest rate           1.00%        
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio between 2.50 to 1.00 and 2.75 to 1.00 | Maximum                    
Debt Instrument [Line Items]                    
Covenant compliance, debt to EBITDAX ratio       2.75            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio between 2.50 to 1.00 and 2.75 to 1.00 | Minimum                    
Debt Instrument [Line Items]                    
Covenant compliance, debt to EBITDAX ratio       2.50            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio between 2.75 to 1.00 and 3.00 to 1.00                    
Debt Instrument [Line Items]                    
Increase in interest rate           2.00%        
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio between 2.75 to 1.00 and 3.00 to 1.00 | Maximum                    
Debt Instrument [Line Items]                    
Covenant compliance, debt to EBITDAX ratio       3.00            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio between 2.75 to 1.00 and 3.00 to 1.00 | Minimum                    
Debt Instrument [Line Items]                    
Covenant compliance, debt to EBITDAX ratio       2.75            
8.5% Second Lien Notes due 2023 | Second Lien Notes | Debt to EBITDAX Ratio Greater than or Equal to 3.00 to 1.00                    
Debt Instrument [Line Items]                    
Covenant compliance, debt to EBITDAX ratio       3.00            
Increase in interest rate           3.00%        
8.5% Second Lien Notes due 2023 | Second Lien Notes | Exchange Agreement                    
Debt Instrument [Line Items]                    
Junior subordinated notes       $ 344,300,000     4,300,000      
Principal repaid               10,100,000    
8% Senior Notes due 2020                    
Debt Instrument [Line Items]                    
Notes exchanged             0 $ 0 $ 590,041,000  
8% Senior Notes due 2020 | Senior Notes                    
Debt Instrument [Line Items]                    
Interest rate percentage       8.00%            
Unsecured Ven Bakken Note | Unsecured Debt                    
Debt Instrument [Line Items]                    
Interest rate percentage     6.00%              
Principal amount     $ 130,000,000.0              
Percent of principal amount required to be repaid by the company before January 1, 2021     50.00%              
Revolving Credit Facility                    
Debt Instrument [Line Items]                    
Number of days before maturity date 91 days                  
Current borrowing capacity             $ 660,000,000.0      
Covenant compliance, debt to EBITDAX ratio 3.50                  
Covenant compliance, current ratio 1.00                  
Security interests as a percent of properties 90.00%                  
Revolving Credit Facility | Federal Funds                    
Debt Instrument [Line Items]                    
Interest rate margin in effect during period 0.50%                  
Revolving Credit Facility | LIBOR                    
Debt Instrument [Line Items]                    
Interest rate margin in effect during period             1.00%      
Revolving Credit Facility | Maximum | LIBOR                    
Debt Instrument [Line Items]                    
Interest rate margin in effect during period             3.00%      
Revolving Credit Facility | Maximum | Base Rate                    
Debt Instrument [Line Items]                    
Interest rate margin in effect during period             2.00%      
Revolving Credit Facility | Minimum | LIBOR                    
Debt Instrument [Line Items]                    
Interest rate margin in effect during period             2.00%      
Revolving Credit Facility | Minimum | Base Rate                    
Debt Instrument [Line Items]                    
Interest rate margin in effect during period             1.00%