cm:Concept: us-gaap:DiscussionOfForeignCurrencyFairValueHedgeEffectivenessAssessmentAndMeasurement
| Discussion of Foreign Currency Fair Value Hedge Effectiveness Assessment and Measurement |
| us-gaap:DiscussionOfForeignCurrencyFairValueHedgeEffectivenessAssessmentAndMeasurement |
| Discussion of how the entity assesses hedge effectiveness and measures hedge ineffectiveness in foreign currency fair value hedges. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DiscussionOfForeignCurrencyFairValueHedgeEffectivenessAssessmentAndMeasurement |