cm:Concept: us-gaap:WeightedAverageNumberOfSharesOutstandingBasic
| Weighted Average Number of Shares Outstanding, Basic |
| us-gaap:WeightedAverageNumberOfSharesOutstandingBasic |
| Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:WeightedAverageNumberOfSharesOutstandingBasic |