Basis of Presentation (Tables)
   | 
6 Months Ended | 
Jun. 30, 2021  | 
| Notes Tables | 
 
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| Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block] | 
  
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  | 
  | 
June 30, 2021  | 
  | 
December 31, 2020  | 
 
Derivatives – current (1)  | 
  | 
$  | 
 14,021  | 
  | 
$  | 
 2,752  | 
 
Unamortized insurance/bond premiums  | 
  | 
   | 
 6,195  | 
  | 
   | 
 4,717  | 
 
Prepaid deposits related to royalties  | 
  | 
   | 
 4,544  | 
  | 
   | 
 4,473  | 
 
Prepayment to vendors  | 
  | 
   | 
 4,775  | 
  | 
   | 
 1,429  | 
 
Other  | 
  | 
   | 
 1,170  | 
  | 
   | 
 461  | 
 
Prepaid expenses and other assets  | 
  | 
$  | 
 30,705  | 
  | 
$  | 
 13,832  | 
 
 
(1)  | 
Includes closed contracts which have not yet settled.  | 
  
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| Property, Plant and Equipment [Table Text Block] | 
  
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  | 
  | 
June 30, 2021  | 
  | 
December 31, 2020  | 
 
Oil and natural gas properties and equipment, at cost  | 
  | 
$  | 
 8,583,983  | 
  | 
$  | 
 8,567,509  | 
 
Furniture, fixtures and other  | 
  | 
   | 
 20,845  | 
  | 
   | 
 20,847  | 
 
Total property and equipment  | 
  | 
   | 
 8,604,828  | 
  | 
   | 
 8,588,356  | 
 
Less: Accumulated depreciation, depletion, amortization and impairment  | 
  | 
   | 
 7,947,171  | 
  | 
   | 
 7,901,478  | 
 
Oil and natural gas properties and other, net  | 
  | 
$  | 
 657,657  | 
  | 
$  | 
 686,878  | 
 
 
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| Schedule of Other Assets, Noncurrent [Table Text Block] | 
  
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  | 
  | 
June 30, 2021  | 
  | 
December 31, 2020  | 
 
Right-of-Use assets  | 
  | 
$  | 
 10,783  | 
  | 
$  | 
 11,509  | 
 
Unamortized debt issuance costs  | 
  | 
   | 
 1,333  | 
  | 
   | 
 2,094  | 
 
Investment in White Cap, LLC  | 
  | 
   | 
 2,995  | 
  | 
   | 
 2,699  | 
 
Unamortized brokerage fee for Monza  | 
  | 
   | 
 —  | 
  | 
   | 
 626  | 
 
Proportional consolidation of Monza's other assets (Note 5)  | 
  | 
   | 
 4,209  | 
  | 
   | 
 1,782  | 
 
Derivatives  | 
  | 
   | 
 21,005  | 
  | 
   | 
 2,762  | 
 
Other  | 
  | 
   | 
 2,070  | 
  | 
   | 
 998  | 
 
Total other assets (long-term)  | 
  | 
$  | 
 42,395  | 
  | 
$  | 
 22,470  | 
 
 
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| Schedule of Accrued Liabilities [Table Text Block] | 
  
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  | 
  | 
June 30, 2021  | 
  | 
December 31, 2020  | 
 
Accrued interest  | 
  | 
$  | 
 10,185  | 
  | 
$  | 
 10,389  | 
 
Accrued salaries/payroll taxes/benefits  | 
  | 
   | 
 4,218  | 
  | 
   | 
 4,009  | 
 
Litigation accruals  | 
  | 
   | 
 570  | 
  | 
   | 
 436  | 
 
Lease liability  | 
  | 
   | 
 673  | 
  | 
   | 
 394  | 
 
Derivatives  | 
  | 
   | 
 82,832  | 
  | 
   | 
 13,620  | 
 
Other  | 
  | 
   | 
 1,885  | 
  | 
   | 
 1,032  | 
 
Total accrued liabilities  | 
  | 
$  | 
 100,363  | 
  | 
$  | 
 29,880  | 
 
 
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| Other Noncurrent Liabilities [Table Text Block] | 
  
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  | 
  | 
June 30, 2021  | 
  | 
December 31, 2020  | 
 
Dispute related to royalty deductions  | 
  | 
$  | 
 5,247  | 
  | 
$  | 
 5,467  | 
 
Derivatives  | 
  | 
   | 
 28,122  | 
  | 
   | 
 4,384  | 
 
Lease liability  | 
  | 
   | 
 11,062  | 
  | 
   | 
 11,360  | 
 
Black Elk escrow  | 
  | 
   | 
 11,102  | 
  | 
   | 
 11,103  | 
 
Other  | 
  | 
   | 
 726  | 
  | 
   | 
 624  | 
 
Total other liabilities (long-term)  | 
  | 
$  | 
 56,259  | 
  | 
$  | 
 32,938  | 
 
 
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