cm:Concept: us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
| Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate |
| us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate |
| Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. |
| cm:Concept |
| Percent (num:percentItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate |