cm:Concept: us-gaap:EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquityAccountingTreatment
| Equity Method Investment, Difference Between Carrying Amount and Underlying Equity, Accounting Treatment |
| us-gaap:EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquityAccountingTreatment |
| Description of the accounting treatment for the difference between the amount at which an investment accounted for under the equity method of accounting is reported on the balance sheet and the amount of underlying equity in net assets the reporting entity has in the investee. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquityAccountingTreatment |