cm:Concept: us-gaap:StockIssuedDuringPeriodSharesDividendReinvestmentPlan
| Stock Issued During Period, Shares, Dividend Reinvestment Plan |
| us-gaap:StockIssuedDuringPeriodSharesDividendReinvestmentPlan |
| Number of shares issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the shareholders to reinvest dividends paid to them by the entity on new issues of stock by the entity. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:StockIssuedDuringPeriodSharesDividendReinvestmentPlan |