cm:Concept: us-gaap:NewAccountingPronouncementOrChangeInAccountingPrincipleDescriptionOfPriorperiodInformationRetrospectivelyAdjusted
       
          
          | New Accounting Pronouncement or Change in Accounting Principle, Description of Prior-period Information Retrospectively Adjusted | 
       
       
          
          | us-gaap:NewAccountingPronouncementOrChangeInAccountingPrincipleDescriptionOfPriorperiodInformationRetrospectivelyAdjusted | 
       
       
          
          | Description of the prior-period information that has been retrospectively adjusted when a new accounting pronouncement or a change in accounting principle is adopted. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Text/String (xbrli:stringItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:NewAccountingPronouncementOrChangeInAccountingPrincipleDescriptionOfPriorperiodInformationRetrospectivelyAdjusted |