cm:Concept: us-gaap:WeightedAverageNumberOfSharesRestrictedStock
| Weighted Average Number of Shares, Restricted Stock |
| us-gaap:WeightedAverageNumberOfSharesRestrictedStock |
| Number of shares of restricted stock determined by relating the portion of time within a reporting period that restricted shares have been outstanding to the total time in that period. Restricted shares are subject to sales, contractual, regulatory or other restrictions that prevent or inhibit the holder from freely disposing of them before the restriction ends. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:WeightedAverageNumberOfSharesRestrictedStock |