cm:Concept: us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding
| Weighted Average Number of Shares Outstanding, Diluted |
| us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding |
| The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding |