cm:Concept: us-gaap:UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions
| Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions |
| us-gaap:UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions |
| Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions |