cm:Concept: us-gaap:WeightedAverageNumberOfSharesIssuedBasic
| Weighted Average Number of Shares Issued, Basic |
| us-gaap:WeightedAverageNumberOfSharesIssuedBasic |
| This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic). |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:WeightedAverageNumberOfSharesIssuedBasic |