cm:Level3TextBlock: us-gaap:ScheduleOfChangeInAccountingEstimateTextBlock
       
          
          | Schedule of Change in Accounting Estimate [Table Text Block] | 
       
       
          
          | us-gaap:ScheduleOfChangeInAccountingEstimateTextBlock | 
       
       
          
          | Tabular disclosure of the change in an accounting estimate, including a change that occurs in an interim period. If a change in accounting estimate affects several future periods (for example, a change in the service life of a depreciable asset) disclose the effect on income from continuing operations, net income (or other appropriate captions of changes in the applicable net assets or performance indicator), and any related per-share amounts of the current period. Disclosure of the effects of a change in an accounting estimate that occurs in the ordinary course of business (such as uncollectible accounts or inventory obsolescence) is not required, unless the effect is material. | 
       
       
          
          | cm:Level3TextBlock | 
       
       
          
          | Text Block (HTML) (nonnum:textBlockItemType) | 
       
       
          
          | For Period (duration) | 
       
       
          
          | (no balance type) | 
       
       
          
          | false | 
       
       
          
          | us-gaap:ScheduleOfChangeInAccountingEstimateTextBlock | 
       
       
          
          | ChangeInAccountingEstimate |