cm:Level3TextBlock: us-gaap:RecordedUnconditionalPurchaseObligationsTextBlock
       
          
          | Recorded Unconditional Purchase Obligations [Table Text Block] | 
       
       
          
          | us-gaap:RecordedUnconditionalPurchaseObligationsTextBlock | 
       
       
          
          | Tabular disclosure of unconditional purchase obligations that are recognized as a liability on the balance sheet, including the nature and term of the unconditional purchase obligations; the aggregate amount of payments for each of the five years following the date of the latest balance sheet; and the combined aggregate amount of maturities and sinking fund requirements for all long-term borrowings associated with suppliers' financing arrangements. | 
       
       
          
          | cm:Level3TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:RecordedUnconditionalPurchaseObligationsTextBlock |