cm:Concept: us-gaap:ResaleAgreementsPolicyForMonitoringOfMarketValueOfUnderlyingAssets
| Resale Agreements, Policy for Monitoring of Market Value of Underlying Assets |
| us-gaap:ResaleAgreementsPolicyForMonitoringOfMarketValueOfUnderlyingAssets |
| This describes the entity's provisions to ensure that the market value of the underlying assets remains sufficient to protect the entity in the event of default by the counterparty. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ResaleAgreementsPolicyForMonitoringOfMarketValueOfUnderlyingAssets |