cm:Concept: us-gaap:MultiemployerPlanCollectiveBargainingArrangementPercentageOfContributionsRequiredForMultipleCollectiveBargainingArrangements
| Multiemployer Plan, Collective-Bargaining Arrangement, Percentage of Contributions Required for Multiple Collective-Bargaining Arrangements |
| us-gaap:MultiemployerPlanCollectiveBargainingArrangementPercentageOfContributionsRequiredForMultipleCollectiveBargainingArrangements |
| Percentage of contributions required of employer under collective bargaining arrangement to total contributions required under all collective bargaining arrangements for pension and other postretirement plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. |
| cm:Concept |
| Percent (num:percentItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:MultiemployerPlanCollectiveBargainingArrangementPercentageOfContributionsRequiredForMultipleCollectiveBargainingArrangements |