cm:Member: us-gaap:QualitativeAndQuantitativeInformationTransferorsContinuingInvolvementInTransferredFinancialAssetsTransferOrTransfereeDomain
       
          
          | Qualitative and Quantitative Information, Transferor's Continuing Involvement in Transferred Financial Assets, Transfer or Transferee [Domain] | 
       
       
          
          | us-gaap:QualitativeAndQuantitativeInformationTransferorsContinuingInvolvementInTransferredFinancialAssetsTransferOrTransfereeDomain | 
       
       
          
          | This item contains a description of the individual transfer (for example, a description of the transaction) or transferee (for example, name of a variable interest entity), to which the entity (transferor) continues to have involvement with the financial assets transferred. | 
       
       
          
          | cm:Member | 
       
       
          
          | [Member] (nonnum:domainItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | true | 
       
       
          
          | us-gaap:QualitativeAndQuantitativeInformationTransferorsContinuingInvolvementInTransferredFinancialAssetsTransferOrTransfereeDomain |