cm:Member: us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember
| Fair Value, Concentration of Credit Risk, Master Netting Arrangements [Member] |
| us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember |
| This element describes the policy of entering into master netting arrangements to mitigate the credit risk of financial instruments (as defined), information about the arrangements for which the entity is a party, and a brief description of the terms of those arrangements, including the extent to which they would reduce the entity's maximum amount of loss due to credit risk. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:FairValueConcentrationOfCreditRiskMasterNettingArrangementsMember |