cm:Concept: us-gaap:IndefiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss
| Indefinite-lived Intangible Assets, Foreign Currency Translation Gain (Loss) |
| us-gaap:IndefiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss |
| Amount of foreign currency translation gain (loss) which increases (decreases) an asset, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:IndefiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss |