cm:Concept: us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsNumberOfShares
| Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Number of Shares |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsNumberOfShares |
| The number of shares that would be issued, determined under the conditions specified in the contract, if the settlement were to occur at the reporting date. |
| cm:Concept |
| Shares (xbrli:sharesItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsNumberOfShares |