cm:Level1TextBlock: us-gaap:CashCashEquivalentsAndShortTermInvestmentsTextBlock
       
          
          | Cash, Cash Equivalents, and Short-term Investments [Text Block] | 
       
       
          
          | us-gaap:CashCashEquivalentsAndShortTermInvestmentsTextBlock | 
       
       
          
          | The entire disclosure of the components of cash, cash equivalents, and short-term investments. Short-term investments may include current marketable securities. | 
       
       
          
          | cm:Level1TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:CashCashEquivalentsAndShortTermInvestmentsTextBlock | 
       
       
          
          | CashCashEquivalentsAndShortTermInvestments |