Annual report pursuant to Section 13 and 15(d)

Long-Term Debt - Additional Information (Details)

v3.20.4
Long-Term Debt - Additional Information (Details)
 3 Months Ended 12 Months Ended
Sep. 30, 2021
May 01, 2020
USD ($)
Dec. 31, 2020
USD ($)
day
Dec. 31, 2020
USD ($)
day
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Oct. 08, 2020
USD ($)
Jul. 27, 2020
USD ($)
Mar. 31, 2020
USD ($)
Nov. 25, 2019
USD ($)
Jul. 31, 2019
USD ($)
Debt Instrument [Line Items]                      
Write off of unamortized issuance costs on debt subject to compromise       $ 21,956,000              
Debtor-in-possession financing, letters of credit outstanding     $ 262,500,000 262,500,000              
Debtor-in-possession financing, amount arranged     105,000,000 105,000,000              
Debtor-in-possession financing, borrowings outstanding     $ 157,500,000 157,500,000              
DIP credit facility financing fees       $ 2,988,000              
Debtor-in-possession financing, number of business days after petition date to terminate | day     3 3              
Debtor-in-possession financing, number of dates after the entry of the interim order to terminate | day     35 35              
Gain on extinguishment of debt       $ 49,579,000 $ 48,630,000 $ 0          
Capitalized interest       (907,000) (3,372,000) (4,470,000)          
Oil and gas properties                      
Debt Instrument [Line Items]                      
Capitalized interest       (900,000) (3,400,000) $ (4,500,000)          
Senior notes                      
Debt Instrument [Line Items]                      
Authorized amount     $ 200,000,000 200,000,000             $ 100,000,000
Repurchased face amount     73,300,000 73,300,000              
Repayments of debt       22,800,000              
Gain on extinguishment of debt       49,600,000              
Senior notes | Carrying value                      
Debt Instrument [Line Items]                      
Outstanding debt     1,800,000,000 1,800,000,000              
Senior notes | Fair value                      
Debt Instrument [Line Items]                      
Outstanding debt     1,200,000,000 $ 1,200,000,000              
Building Loan                      
Debt Instrument [Line Items]                      
Fixed interest rate on outstanding principal       4.50%              
Credit facility     21,900,000 $ 21,900,000              
DIP credit facility | Line of Credit                      
Debt Instrument [Line Items]                      
Weight average interest rate       5.50%              
DIP credit facility | Revolving credit facility | Line of Credit                      
Debt Instrument [Line Items]                      
Commitment fee percentage       0.50%              
DIP credit facility | Letter of credit | Line of Credit                      
Debt Instrument [Line Items]                      
Commitment fee percentage       0.20%              
DIP credit facility | Line of Credit                      
Debt Instrument [Line Items]                      
Long-term debt     157,500,000 $ 157,500,000 0            
DIP credit facility | Eurodollar | Line of Credit                      
Debt Instrument [Line Items]                      
Interest rate       4.50%              
DIP credit facility | Base Rate | Line of Credit                      
Debt Instrument [Line Items]                      
Interest rate       3.50%              
Pre-petition revolving credit facility | Revolving credit facility                      
Debt Instrument [Line Items]                      
Borrowing base         700,000,000   $ 580,000,000        
Long-term debt     292,900,000 $ 292,900,000              
Repayments of lines of credit       $ 1,300,000              
Pre-petition revolving credit facility | Revolving credit facility | Nova Scotia, Amegy, KeyBank                      
Debt Instrument [Line Items]                      
Proceeds from line of credit     96,200,000                
Pre-petition revolving credit facility | Revolving credit facility | Line of Credit | Nova Scotia, Amegy, KeyBank                      
Debt Instrument [Line Items]                      
Weight average interest rate       3.15%              
Pre-petition revolving credit facility | Letter of credit                      
Debt Instrument [Line Items]                      
Maximum repayment amount               $ 750,000,000      
Pre-petition revolving credit facility | Letter of credit | Nova Scotia, Amegy, KeyBank                      
Debt Instrument [Line Items]                      
Borrowing base   $ 700,000,000.0             $ 1,000,000,000.0 $ 1,200,000,000  
Maximum net secured debt to EBITDAX ratio   2.00                  
Proceeds from line of credit     171,800,000                
Pre-petition revolving credit facility | Letter of credit | Nova Scotia, Amegy, KeyBank | Prepaid Expenses and Other Current Assets                      
Debt Instrument [Line Items]                      
Long-term line of credit outstanding     111,800,000 $ 111,800,000              
Pre-petition revolving credit facility | Letter of credit | Nova Scotia, Amegy, KeyBank | Forecast                      
Debt Instrument [Line Items]                      
Net funded debt to EBITDAX ratio 4.00                    
Pre-petition revolving credit facility | Letter of credit | Line of Credit | Nova Scotia, Amegy, KeyBank                      
Debt Instrument [Line Items]                      
Long-term line of credit outstanding     147,500,000 147,500,000              
Pre-petition revolving credit facility | Line of Credit                      
Debt Instrument [Line Items]                      
Long-term debt     $ 292,910,000 $ 292,910,000 $ 120,000,000