| Standard label: | Oil and Gas Properties [Text Block] | 
| Name: | us-gaap:OilAndGasPropertiesTextBlock | 
| Documentation: | The entire disclosure for properties used in normal conduct of oil and gas exploration and producing operations. This disclosure may include property accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives. | 
| Object type: | cm:Level1TextBlock | 
| Data type: | Text Block (HTML) (nonnum:textBlockItemType) | 
| Period type: | For Period (duration) | 
| Balance type: | (no balance type) | 
| Abstract: | false | 
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:OilAndGasPropertiesTextBlock | 
| Label | Role | Language | 
| Oil and Gas Properties [Text Block] | http://www.xbrl.org/2003/role/label | en-US | 
| Reference | Role | Topic | 
| FASB Accounting Standards Codification 932 360 | http://fasb.org/us-gaap/role/ref/legacyRef | 932 |