cm:Concept: us-gaap:GoodwillImpairedFactsAndCircumstancesLeadingToImpairment
| Goodwill, Impaired, Facts and Circumstances Leading to Impairment |
| us-gaap:GoodwillImpairedFactsAndCircumstancesLeadingToImpairment |
| Description of the underlying cause of impairment of goodwill, such as a significant and more than temporary reduction in sales of a business unit. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:GoodwillImpairedFactsAndCircumstancesLeadingToImpairment |