cm:Concept: us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsNumberOfSharesIndexed
| Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Number of Shares Indexed |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsNumberOfSharesIndexed |
| For a forward contract or an option indexed to the issuer's equity shares, the number of issuer's shares to which the contract is indexed. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsNumberOfSharesIndexed |