cm:Concept: us-gaap:SecuritiesBorrowedNotSubjectToMasterNettingArrangementDeduction
       
          
          | Securities Borrowed, Not Subject to Master Netting Arrangement Deduction | 
       
       
          
          | us-gaap:SecuritiesBorrowedNotSubjectToMasterNettingArrangementDeduction | 
       
       
          
          | Amount of securities borrowed from entities in exchange for collateral, not subject to a master netting arrangement, deducted from securities borrowed. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | As Of (instant) | 
       
       
          
          | Credit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:SecuritiesBorrowedNotSubjectToMasterNettingArrangementDeduction |