cm:Concept: us-gaap:IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions
       
          
          | Income (Loss) from Equity Method Investments, Net of Dividends or Distributions | 
       
       
          
          | us-gaap:IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions | 
       
       
          
          | This element represents the undistributed income (or loss) of equity method investments, net of dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporations; such investments are accounted for under the equity method of accounting. This element excludes distributions that constitute a return of investment, which are classified as investing activities. | 
       
       
          
          | cm:Concept | 
       
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | Credit | 
       
       
          
          | false | 
       
       
          
          | us-gaap:IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions |