cm:Member: us-gaap:MultiemployerPlanIndividuallyInsignificantMultiemployerPlansMember
| Multiemployer Plan, Individually Insignificant Multiemployer Plans [Member] |
| us-gaap:MultiemployerPlanIndividuallyInsignificantMultiemployerPlansMember |
| Individually insignificant pension or postretirement benefit plans to which two or more unrelated employers contribute to the same plan where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:MultiemployerPlanIndividuallyInsignificantMultiemployerPlansMember |