cm:Concept: us-gaap:ProceedsFromPaymentsForInInterestBearingDepositsInBanks
| Proceeds from (Payments for) in Interest-bearing Deposits in Banks |
| us-gaap:ProceedsFromPaymentsForInInterestBearingDepositsInBanks |
| The net cash inflow or outflow in Interest-bearing Deposits by banks in other financial institutions for relatively short periods of time including, for example, certificates of deposits. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:ProceedsFromPaymentsForInInterestBearingDepositsInBanks |