cm:Concept: us-gaap:RepaymentsOfAdvancesForConstruction
       
          
          | Repayments of Advances for Construction | 
       
       
          
          | us-gaap:RepaymentsOfAdvancesForConstruction | 
       
       
          
          | The cash outflow for the payments made by the entity, generally on a straight-line basis over periods ranging from five to forty years to developers, builders, government agencies and municipalities for borrowings received in construction. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | Credit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:RepaymentsOfAdvancesForConstruction |