cm:Level3TextBlock: us-gaap:ScheduleOfOtherNonoperatingIncomeByComponentTextBlock
       
          
          | Schedule of Other Nonoperating Income, by Component [Table Text Block] | 
       
       
          
          | us-gaap:ScheduleOfOtherNonoperatingIncomeByComponentTextBlock | 
       
       
          
          | Tabular disclosure of the detailed components of other nonoperating income. May include methodology, assumptions and amounts for: (a) dividends, (b) interest on securities, (c) profits on securities (net of losses), and (d) miscellaneous other income items. | 
       
       
          
          | cm:Level3TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:ScheduleOfOtherNonoperatingIncomeByComponentTextBlock |