cm:Level3TextBlock: us-gaap:ScheduleOfUnusualOrInfrequentItemsTextBlock
       
          
          | Schedule of Unusual or Infrequent Items, or Both [Table Text Block] | 
       
       
          
          | us-gaap:ScheduleOfUnusualOrInfrequentItemsTextBlock | 
       
       
          
          | Tabular disclosure of the nature and financial statement effect of an event or transaction that is unusual in nature or infrequent in occurrence, or both. | 
       
       
          
          | cm:Level3TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:ScheduleOfUnusualOrInfrequentItemsTextBlock | 
       
       
          
          | UnusualOrInfrequentItem |