cm:Concept: us-gaap:SecuritiesBorrowedGrossIncludingNotSubjectToMasterNettingArrangement
       
          
          | Securities Borrowed, Gross Including Not Subject to Master Netting Arrangement | 
       
       
          
          | us-gaap:SecuritiesBorrowedGrossIncludingNotSubjectToMasterNettingArrangement | 
       
       
          
          | Amount, before effects of master netting arrangements, of securities borrowed from entities in exchange for collateral. Includes assets not subject to a master netting arrangement and elected not to be offset. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | As Of (instant) | 
       
       
          
          | Debit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:SecuritiesBorrowedGrossIncludingNotSubjectToMasterNettingArrangement |