cm:Member: us-gaap:FairValueConcentrationOfRiskDisclosureItemsDomain
| Fair Value, Concentration of Risk, Disclosure Items [Domain] |
| us-gaap:FairValueConcentrationOfRiskDisclosureItemsDomain |
| Provides the general information items required or determined to be disclosed with respect to all significant concentrations of risk, including credit risk and market risk, arising from all financial instruments (as defined), whether from an individual counterparty or groups of counterparties. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:FairValueConcentrationOfRiskDisclosureItemsDomain |