cm:Member: us-gaap:DerivativesSubjectToMandatoryRedemptionMember
| Derivatives Subject to Mandatory Redemption [Member] |
| us-gaap:DerivativesSubjectToMandatoryRedemptionMember |
| Options and forward contracts that require physical settlement by repurchase of a fixed number of the issuer's equity shares in exchange for cash or that embody an unconditional obligation requiring the issuer to redeem the instrument by transferring its assets at a specified or determinable date (or dates) or upon an event certain to occur. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:DerivativesSubjectToMandatoryRedemptionMember |