Quarterly report pursuant to Section 13 or 15(d)

LONG-TERM DEBT - Narrative (Details)

v3.21.1
LONG-TERM DEBT - Narrative (Details)
3 Months Ended
Feb. 18, 2021
USD ($)
Jan. 04, 2021
USD ($)
Nov. 22, 2019
USD ($)
Jul. 01, 2019
USD ($)
Mar. 31, 2021
USD ($)
Mar. 31, 2020
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
USD ($)
Nov. 30, 2019
USD ($)
Oct. 31, 2018
USD ($)
May 31, 2018
USD ($)
May 15, 2018
Debt Instrument [Line Items]                        
Proceeds from issuance of common stock         $ 132,900,000 $ 0            
Long-term debt, gross         828,669,000   $ 949,755,000          
Long-term debt         817,061,000   944,843,000          
Revolving Credit Facility                        
Debt Instrument [Line Items]                        
Long-term debt, gross         263,000,000   532,000,000          
Borrowing base     $ 660,000,000.0                  
Maximum debt to EBITDAX ratio under debt covenant     3.50                  
Minimum current ratio under debt covenant     1.00                  
Minimum percent of the fair value of reserves secured by mortgages     90.00%                  
Revolving Credit Facility | Federal funds effective rate                        
Debt Instrument [Line Items]                        
Basis spread on variable rate     0.50%                  
Revolving Credit Facility | LIBOR                        
Debt Instrument [Line Items]                        
Basis spread on variable rate     1.00%                  
Revolving Credit Facility | LIBOR | Minimum                        
Debt Instrument [Line Items]                        
Basis spread on variable rate     2.00%                  
Revolving Credit Facility | LIBOR | Maximum                        
Debt Instrument [Line Items]                        
Basis spread on variable rate     3.00%                  
Revolving Credit Facility | Base rate | Minimum                        
Debt Instrument [Line Items]                        
Basis spread on variable rate     1.00%                  
Revolving Credit Facility | Base rate | Maximum                        
Debt Instrument [Line Items]                        
Basis spread on variable rate     2.00%                  
Unsecured Debt | VEN Bakken LLC                        
Debt Instrument [Line Items]                        
Interest rate       6.00%                
Unsecured Notes due 2028 | Unsecured Debt                        
Debt Instrument [Line Items]                        
Principal amount $ 550,000,000.0       $ 550,000,000.0              
Interest rate 8.125%       8.125%              
Proceeds from the issuance of long-term debt         $ 538,400,000              
Long-term debt, gross         550,000,000   0          
Default period 30 days                      
Acceleration threshold amount $ 35,000,000.0                      
Judgment discharge or stay period 60 days                      
Unsecured Notes due 2028 | Unsecured Debt | Redemption Period 1                        
Debt Instrument [Line Items]                        
Redemption price, percentage of principal amount repurchased 100.00%                      
Unsecured Notes due 2028 | Unsecured Debt | Redemption Period 2                        
Debt Instrument [Line Items]                        
Redemption price percentage 104.063%                      
Unsecured Notes due 2028 | Unsecured Debt | Redemption Period 3                        
Debt Instrument [Line Items]                        
Redemption price percentage 102.031%                      
Unsecured Notes due 2028 | Unsecured Debt | Redemption Period 4                        
Debt Instrument [Line Items]                        
Redemption price percentage 100.00%                      
Unsecured VEN Bakken Note due 2022 | VEN Bakken LLC                        
Debt Instrument [Line Items]                        
Interest rate       6.00%                
Percent of principal       50.00%                
Unsecured VEN Bakken Note due 2022 | Unsecured Debt                        
Debt Instrument [Line Items]                        
Principal amount       $ 130,000,000.0                
Long-term debt, gross         0   130,000,000          
Repayments of long-term debt $ 65,000,000.0 $ 65,000,000.0                    
Second Lien Notes due 2023 | Second Lien Notes                        
Debt Instrument [Line Items]                        
Interest rate                       8.50%
Long-term debt, gross         15,669,000   287,755,000          
Additional face amount issued                   $ 350,000,000.0    
Second Lien Notes due 2023 | Second Lien Notes | Exchange Agreement                        
Debt Instrument [Line Items]                        
Principal amount                     $ 344,300,000  
Additional face amount issued         4,300,000              
Long-term debt         15,700,000              
Second Lien Notes due 2023 | Second Lien Notes | Cash Tender Offer                        
Debt Instrument [Line Items]                        
Aggregate principal amount of debt repurchased and retired         272,100,000   13,500,000   $ 200,000,000.0      
Cost of redemption and retirement of debt, including premiums         $ 280,200,000              
Second Lien Notes due 2023 | Second Lien Notes | Open Market Transactions                        
Debt Instrument [Line Items]                        
Aggregate principal amount of debt repurchased and retired               $ 10,100,000        
Second Lien Notes due 2023 | Second Lien Notes | Exchange for Shares of Series A Preferred Stock                        
Debt Instrument [Line Items]                        
Aggregate principal amount of debt repurchased and retired             $ 116,500,000   $ 70,800,000      
8.000% Senior Notes due 2020 | Unsecured Debt                        
Debt Instrument [Line Items]                        
Interest rate                     8.00%