cm:Concept: us-gaap:PledgedFinancialInstrumentsNotSeparatelyReportedMortgageRelatedSecuritiesHeldToMaturity
| Pledged Financial Instruments, Not Separately Reported, Mortgage-Related Securities Held-to-maturity |
| us-gaap:PledgedFinancialInstrumentsNotSeparatelyReportedMortgageRelatedSecuritiesHeldToMaturity |
| The carrying amount as of the date of the latest financial statement presented of mortgage-related 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:PledgedFinancialInstrumentsNotSeparatelyReportedMortgageRelatedSecuritiesHeldToMaturity |