cm:Member: us-gaap:DefinedBenefitPlanCommonCollectiveTrustMember
| Defined Benefit Plan, Common Collective Trust [Member] |
| us-gaap:DefinedBenefitPlanCommonCollectiveTrustMember |
| Regulated trust, responsible for collective investment and reinvestment of asset from employee benefit plan maintained by more than one employer, in which defined benefit plan asset is invested. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:DefinedBenefitPlanCommonCollectiveTrustMember |