cm:Concept: us-gaap:SubsidiaryOrEquityMethodInvesteeDeferredIncomeTaxProvisionOnCumulativeGainLossRecognized
| Subsidiary or Equity Method Investee, Deferred Income Tax Provision on Gain (Loss) Recognized [true false] |
| us-gaap:SubsidiaryOrEquityMethodInvesteeDeferredIncomeTaxProvisionOnCumulativeGainLossRecognized |
| Indicates if deferred income taxes have been provided for a gain (loss) recognized in income of the entity resulting from the issuance of shares by a subsidiary or equity method investee. |
| cm:Concept |
| Yes/No (xbrli:booleanItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SubsidiaryOrEquityMethodInvesteeDeferredIncomeTaxProvisionOnCumulativeGainLossRecognized |