cm:Member: us-gaap:CustomerSecuritiesForWhichEntityHasRightToSellOrRepledgeSecuritiesTypeDomain
       
          
          | Customer Securities for which Entity has Right to Sell or Repledge, Securities Type [Domain] | 
       
       
          
          | us-gaap:CustomerSecuritiesForWhichEntityHasRightToSellOrRepledgeSecuritiesTypeDomain | 
       
       
          
          | Description of financial instrument type of customer securities accepted by the entity and re-pledged to counterparties as collateral or sold. | 
       
       
          
          | cm:Member | 
       
       
          
          | [Member] (nonnum:domainItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | true | 
       
       
          
          | us-gaap:CustomerSecuritiesForWhichEntityHasRightToSellOrRepledgeSecuritiesTypeDomain |