cm:Concept: us-gaap:StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased
| Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased |
| us-gaap:StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased |
| The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased |