cm:Concept: us-gaap:IncreaseDecreaseInCustomerDeposits
| Increase (Decrease) in Customer Deposits |
| us-gaap:IncreaseDecreaseInCustomerDeposits |
| The increase (decrease) during the period in the amount of customer money held in customer accounts, including security deposits, collateral for a current or future transactions, 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) |
| Debit |
| false |
| us-gaap:IncreaseDecreaseInCustomerDeposits |