cm:Level3TextBlock: us-gaap:ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTableTextBlock
       
          
          | Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Table Text Block] | 
       
       
          
          | us-gaap:ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTableTextBlock | 
       
       
          
          | Tabular disclosure for the reconciliation of claims development to the liability for unpaid claims and claim adjustment expense for short-duration insurance contracts. | 
       
       
          
          | cm:Level3TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:ShortdurationInsuranceContractsReconciliationOfClaimsDevelopmentToLiabilityTableTextBlock |