cm:Level3TextBlock: us-gaap:CapitalizedCostsRelatingToOilAndGasProducingActivitiesDisclosureTextBlock
       
          
          | Capitalized Costs Relating to Oil and Gas Producing Activities Disclosure [Table Text Block] | 
       
       
          
          | us-gaap:CapitalizedCostsRelatingToOilAndGasProducingActivitiesDisclosureTextBlock | 
       
       
          
          | Tabular disclosure of aggregate capitalized costs relating to an enterprise's oil and gas producing activities and the aggregate related accumulated depreciation, depletion, amortization, and valuation allowances. | 
       
       
          
          | cm:Level3TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:CapitalizedCostsRelatingToOilAndGasProducingActivitiesDisclosureTextBlock |