cm:Concept: us-gaap:GoodwillForeignCurrencyTranslationGainLoss
| Goodwill, Foreign Currency Translation Gain (Loss) |
| us-gaap:GoodwillForeignCurrencyTranslationGainLoss |
| Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:GoodwillForeignCurrencyTranslationGainLoss |