|**Revenue Recognition Revenue Recognition (Tables)**              | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
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|**Revenue from Contract with Customer [Abstract]**                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Disaggregation of Revenue [Table Text Block]                      | Disaggregated Revenue.The following table presents crude oil, natural gas and NGLs sales disaggregated by commodity and operating region for the periods presented:Year Ended December 31,Revenue by Commodity and Operating Region202120202019(in thousands)Crude oilWattenberg Field$1,275,666$668,948$767,760Delaware Basin255,135147,902252,929Total1,530,801816,8501,020,689Natural gasWattenberg Field458,870171,755137,143Delaware Basin60,7336,99713,877Total519,603178,752151,020NGLsWattenberg Field428,570128,12694,347Delaware Basin73,58428,82741,219Total502,154156,953135,566Crude oil, natural gas and NGLsWattenberg Field2,163,106968,829999,250Delaware Basin389,452183,726308,025Total$2,552,558$1,152,555$1,307,275
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|Revenue by Commodity and Operating Region                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
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|Crude oil                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Wattenberg Field                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Delaware Basin                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Total                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Natural gas                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Wattenberg Field                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Delaware Basin                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Total                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|NGLs                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Wattenberg Field                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Delaware Basin                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Total                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Crude oil, natural gas and NGLs                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Wattenberg Field                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Delaware Basin                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Total                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
|Contract with Customer, Asset and Liability                       | December 31,20212020(in thousands)Beginning balance$25,872$11,494Additions (Net reduction to additions previously recognized)(7,705)16,739Amortized as a reduction to crude oil, natural gas and NGLs sales(2,695)(2,361)Ending balance$15,472$25,872                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
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|                                                                  | December 31,                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|                                                                  | 2021                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    
|                                                                  | (in thousands)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
|Beginning balance                                                 | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       
|Additions (Net reduction to additions previously recognized)      | (7,705)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Amortized as a reduction to crude oil, natural gas and NGLs sales | (2,695)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 
|Ending balance                                                    | $                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

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