cm:Concept: us-gaap:SecuritiesLoanedAndSecuritiesSoldUnderAgreementToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement
       
          
          | Securities Loaned and Securities Sold under Agreement to Repurchase, Gross Including Not Subject to Master Netting Arrangement | 
       
       
          
          | us-gaap:SecuritiesLoanedAndSecuritiesSoldUnderAgreementToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement | 
       
       
          
          | Amount, before effects of master netting arrangements, of securities loaned to entities in exchange for collateral and 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 not subject to a master netting arrangement. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | As Of (instant) | 
       
       
          
          | Credit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:SecuritiesLoanedAndSecuritiesSoldUnderAgreementToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement |