cm:Concept: us-gaap:UnrecognizedTaxBenefitsIncreasesResultingFromSettlementsWithTaxingAuthorities
| Unrecognized Tax Benefits, Increase Resulting from Settlements with Taxing Authorities |
| us-gaap:UnrecognizedTaxBenefitsIncreasesResultingFromSettlementsWithTaxingAuthorities |
| Amount of increase in unrecognized tax benefits resulting from settlements with taxing authorities. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:UnrecognizedTaxBenefitsIncreasesResultingFromSettlementsWithTaxingAuthorities |