cm:Concept: us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsContractLimit
| Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Contract Limit |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsContractLimit |
| Disclosure that a contract does not limit the amount the issuer could be required to pay or the number of shares that the issuer could be required to issue, if applicable. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsContractLimit |