cm:Member: us-gaap:FairValueConcentrationOfRiskCollateralPolicyMember
| Fair Value, Concentration of Risk, Collateral Policy [Member] |
| us-gaap:FairValueConcentrationOfRiskCollateralPolicyMember |
| This elements represents a description of the policy governing collateral or other security requirements in support of financial instruments (as defined) subject to credit risk, information about access to that collateral or other security, and the nature and a brief description of the collateral or other security supporting those financial instruments (as defined). |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:FairValueConcentrationOfRiskCollateralPolicyMember |