cm:Concept: us-gaap:IncreaseDecreaseInDepositsOutstanding
| Increase (Decrease) in Deposits Outstanding |
| us-gaap:IncreaseDecreaseInDepositsOutstanding |
| The increase (decrease) during the reporting period in monies given as security or collateral for items acquired or borrowed on a temporary basis. Deposits may also be paid as initial payment of the cost of acquisition or for the right to enter into a contract or agreement. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:IncreaseDecreaseInDepositsOutstanding |