cm:Concept: us-gaap:GainFromComponentsExcludedFromAssessmentOfCashFlowHedgeEffectiveness
| Gain from Components Excluded from Assessment of Cash Flow Hedge Effectiveness |
| us-gaap:GainFromComponentsExcludedFromAssessmentOfCashFlowHedgeEffectiveness |
| The gain relating to components of the gain (loss) on the cash flow hedging instrument excluded from the assessment of cash flow hedge effectiveness. Recognized in earnings. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:GainFromComponentsExcludedFromAssessmentOfCashFlowHedgeEffectiveness |