cm:Concept: us-gaap:NewAccountingPronouncementOrChangeInAccountingPrinciplePriorPeriodNotRestated
       
          
          | New Accounting Pronouncement or Change in Accounting Principle, Prior Period Not Restated [true false] | 
       
       
          
          | us-gaap:NewAccountingPronouncementOrChangeInAccountingPrinciplePriorPeriodNotRestated | 
       
       
          
          | Indicates (true false) whether prior period was not restated when there is change in accounting principle or adoption of new accounting pronouncement. Excludes correction of error. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Yes/No (xbrli:booleanItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:NewAccountingPronouncementOrChangeInAccountingPrinciplePriorPeriodNotRestated |