cm:Level2TextBlock: us-gaap:DerivativesReportingOfDerivativeActivity
| Derivatives, Reporting of Derivative Activity [Policy Text Block] |
| us-gaap:DerivativesReportingOfDerivativeActivity |
| Disclosure of accounting policy for derivatives entered into for trading purposes and those entered into for purposes other than trading including where and when derivative financial instruments and derivative commodity instruments and their related gains or losses are reported in the entity's statements of financial position, cash flows, and results of operations. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DerivativesReportingOfDerivativeActivity |