cm:Level3TextBlock: us-gaap:ScheduleOfForeignExchangeContractsStatementOfFinancialPositionTableTextBlock
       
          
          | Schedule of Foreign Exchange Contracts, Statement of Financial Position [Table Text Block] | 
       
       
          
          | us-gaap:ScheduleOfForeignExchangeContractsStatementOfFinancialPositionTableTextBlock | 
       
       
          
          | Tabular disclosure of the presentation of foreign exchange contracts on the statement of financial position, including the fair value amounts and location of such amounts. | 
       
       
          
          | cm:Level3TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:ScheduleOfForeignExchangeContractsStatementOfFinancialPositionTableTextBlock |