cm:Concept: us-gaap:GrandfatheredESOPExpenseRecognitionActualInterestIncurredOnESOPDebt
       
          
          | Grandfathered ESOP Expense Recognition, Actual Interest Incurred on ESOP Debt | 
       
       
          
          | us-gaap:GrandfatheredESOPExpenseRecognitionActualInterestIncurredOnESOPDebt | 
       
       
          
          | For grandfathered ESOP shares acquired prior to January 1, 1993, the actual interest incurred on debt for obligations that the employer may secure on behalf of the ESOP. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | Debit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:GrandfatheredESOPExpenseRecognitionActualInterestIncurredOnESOPDebt |