cm:Concept: us-gaap:SecuritiesSoldUnderAgreementsToResellNotOffsetPolicyElectionDeduction
       
          
          | Securities Sold under Agreements to Repurchase, Not Offset, Policy Election Deduction | 
       
       
          
          | us-gaap:SecuritiesSoldUnderAgreementsToResellNotOffsetPolicyElectionDeduction | 
       
       
          
          | Amount of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price, elected not to be offset, deducted from securities sold under agreements to repurchase. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | As Of (instant) | 
       
       
          
          | Debit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:SecuritiesSoldUnderAgreementsToResellNotOffsetPolicyElectionDeduction |