cm:Concept: us-gaap:ImpairedLongLivedAssetsHeldAndUsedFactsAndCircumstancesLeadingToImpairment
| Impaired Long-Lived Assets Held and Used, Facts and Circumstances Leading to Impairment |
| us-gaap:ImpairedLongLivedAssetsHeldAndUsedFactsAndCircumstancesLeadingToImpairment |
| A description of the facts and circumstances leading to the impairment of the long-lived asset held and used. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ImpairedLongLivedAssetsHeldAndUsedFactsAndCircumstancesLeadingToImpairment |