cm:Level2TextBlock: us-gaap:RevenueRecognitionCompletedContractMethod
       
          
          | Revenue Recognition, Completed-Contract Method [Policy Text Block] | 
       
       
          
          | us-gaap:RevenueRecognitionCompletedContractMethod | 
       
       
          
          | Disclosure of accounting policy for revenue recognition for long-term construction-type contracts accounted for using the completed-contract method. This includes the criteria used to determine when a project is substantially complete. If the entity departs from using the completed-contract method for a single contract or a group of contracts, such a departure from the basic policy is disclosed. The disclosure may also describe the accounting for significant changes in estimates. | 
       
       
          
          | cm:Level2TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:RevenueRecognitionCompletedContractMethod |