cm:Concept: us-gaap:SecuritiesSoldUnderAgreementsToRepurchaseGross
       
          
          | Securities Sold under Agreements to Repurchase, Gross | 
       
       
          
          | us-gaap:SecuritiesSoldUnderAgreementsToRepurchaseGross | 
       
       
          
          | Amount, before effects of master netting arrangements, 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. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | As Of (instant) | 
       
       
          
          | Credit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:SecuritiesSoldUnderAgreementsToRepurchaseGross |