cm:Concept: us-gaap:PaymentsForProceedsFromDerivativeInstrumentFinancingActivities
       
          
          | Payments for (Proceeds from) Derivative Instrument, Financing Activities | 
       
       
          
          | us-gaap:PaymentsForProceedsFromDerivativeInstrumentFinancingActivities | 
       
       
          
          | The net cash outflow or inflow from derivative instruments during the period, which are classified as financing activities, excluding those designated as hedging instruments. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | Credit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:PaymentsForProceedsFromDerivativeInstrumentFinancingActivities |