Fair Value Measurements Schedule of Fair Value of Liabilities (Details) - USD ($)
3 Months Ended 12 Months Ended
May 22, 2020
Mar. 15, 2019
Dec. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Nov. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Long-term debt, net     $ 1,068,624,000 $ 1,068,624,000 $ 1,057,389,000  
Proved Property [Member] | Minimum            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Percentage of Undiscounted cash flows exceeding carrying values       30.00%    
Proved Property [Member] | Maximum            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Percentage of Undiscounted cash flows exceeding carrying values     100.00%      
Proved Property [Member] | Fair Value, Nonrecurring [Member]            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Property, Plant, and Equipment, Fair Value Disclosure     $ 179,600,000 $ 179,600,000 771,400,000  
Asset Impairment Charges       591,800,000    
Senior Notes            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Long-term debt, net     738,624,000 738,624,000 882,389,000  
Senior Notes Due 2026 | Senior Notes            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of senior notes     206,955,000 206,955,000 394,480,000  
Long-term debt     289,448,000 289,448,000 400,000,000 $ 400,000,000.0
Senior Notes Due 2027 | Senior Notes            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of senior notes     254,791,000 254,791,000 520,000,000  
Long-term debt   $ 500,000,000.0 356,351,000 356,351,000 500,000,000  
Debt Instrument, Issued Price, Percentage   99.235%        
Senior Secured Note due 2025 | Senior Notes            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of senior notes     114,366,000 114,366,000 0  
Long-term debt $ 127,100,000   127,073,000 127,073,000 0  
Debt Instrument, Issued Price, Percentage 83.44%          
Carrying Value | Senior Notes Due 2026 | Senior Notes            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Long-term debt, net     284,867,000 284,867,000 392,623,000  
Carrying Value | Senior Notes Due 2027 | Senior Notes            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Long-term debt, net     349,856,000 349,856,000 489,766,000  
Carrying Value | Senior Secured Note due 2025 | Senior Notes            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Long-term debt, net     103,902,000 103,902,000 0  
Revolving Credit Facility | Line of Credit            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Fair value of senior notes     330,000,000 330,000,000 175,000,000  
Long-term Debt, Gross     330,000,000 330,000,000 175,000,000  
Long-term debt     330,000,000 330,000,000 175,000,000  
Revolving Credit Facility | Carrying Value | Line of Credit            
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]            
Long-term Debt, Gross     $ 330,000,000 $ 330,000,000 $ 175,000,000