cm:Concept: us-gaap:ProceedsFromDivestitureOfInterestInJointVenture
       
          
          | Proceeds from Divestiture of Interest in Joint Venture | 
       
       
          
          | us-gaap:ProceedsFromDivestitureOfInterestInJointVenture | 
       
       
          
          | The cash inflow from the sale of an investment interest in a joint venture that the reporting entity has not previously accounted for using consolidation or the equity method of accounting. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | Debit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:ProceedsFromDivestitureOfInterestInJointVenture |