|**Asset Retirement Obligations Asset Retirement Obligations (Tables)** | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
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|**Asset Retirement Obligation Disclosure [Abstract]**                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Schedule of Change in Asset Retirement Obligation [Table Text Block]   | The following table presents the changes in carrying amounts of the asset retirement obligations associated with our working interests in crude oil and natural gas properties for the periods presented:Year Ended December 31,20212020(in thousands)Beginning balance$166,570$127,251Obligations incurred with development activities and other4,7506,494Obligations incurred with acquisition—47,673Accretion expense12,08610,072Revisions in estimated cash flows10,6094,742Obligations discharged with asset retirements and divestitures(34,343)(29,662)Asset retirement obligations at end of period159,672166,570Current portion(1)(32,146)(33,933)Long-term portion$127,526$132,637
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|                                                                       | Year Ended December 31,                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|                                                                       | 2021                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
|                                                                       | (in thousands)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
|Beginning balance                                                      | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Obligations incurred with development activities and other             | 4,750                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Obligations incurred with acquisition                                  | —                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           
|Accretion expense                                                      | 12,086                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Revisions in estimated cash flows                                      | 10,609                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      
|Obligations discharged with asset retirements and divestitures         | (34,343)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Asset retirement obligations at end of period                          | 159,672                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
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|Current portion(1)                                                     | (32,146)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|Long-term portion                                                      | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           

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+ ReferencesReference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13201-110859
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