cm:Concept: us-gaap:PledgedFinancialInstrumentsNotSeparatelyReportedOtherDebtSecuritiesHeldToMaturity
| Pledged Financial Instruments, Not Separately Reported, Other Debt Securities Held-to-maturity |
| us-gaap:PledgedFinancialInstrumentsNotSeparatelyReportedOtherDebtSecuritiesHeldToMaturity |
| The carrying amount as of the date of the latest financial statement presented of other debt securities classified as held to maturity which are owned but transferred to another party to serve as collateral to partially or fully secure a debt obligation, repurchase agreement or other current or potential obligation, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:PledgedFinancialInstrumentsNotSeparatelyReportedOtherDebtSecuritiesHeldToMaturity |