cm:Concept: us-gaap:NetChangeAnnuitiesAndInvestmentCertificates
       
          
          | Net Change Annuities and Investment Certificates | 
       
       
          
          | us-gaap:NetChangeAnnuitiesAndInvestmentCertificates | 
       
       
          
          | The cash inflow or outflow for an insurance contract under which the policy holder make a lump sum payment or a series of payments in exchange for periodic payments to the policyholder beginning immediately or at some future date. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | Debit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:NetChangeAnnuitiesAndInvestmentCertificates |