cm:Concept: us-gaap:SubordinatedLongTermDebt
       
          
          | Subordinated Long-term Debt, Noncurrent | 
       
       
          
          | us-gaap:SubordinatedLongTermDebt | 
       
       
          
          | Carrying value as of the balance sheet date of collateralized/uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Subordinated debt places a lender in a lien position behind the primary lender of the company. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | As Of (instant) | 
       
       
          
          | Credit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:SubordinatedLongTermDebt |