cm:Concept: us-gaap:WeightedAverageNumberOfSharesCommonStockSubjectToRepurchaseOrCancellation
| Weighted Average Number of Shares, Common Stock Subject to Repurchase or Cancellation |
| us-gaap:WeightedAverageNumberOfSharesCommonStockSubjectToRepurchaseOrCancellation |
| Number of shares of common stock subject to repurchase or cancellation determined by relating the portion of time within a reporting period that these shares have been outstanding to the total time in that period. Common stock subject to repurchase are outstanding common shares that are contingently returnable (that is, subject to recall). |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:WeightedAverageNumberOfSharesCommonStockSubjectToRepurchaseOrCancellation |