cm:Concept: us-gaap:SiteContingencyUncertaintiesFromJointAndSeveralLiability
| Site Contingency, Uncertainties from Joint and Several Liability |
| us-gaap:SiteContingencyUncertaintiesFromJointAndSeveralLiability |
| Uncertainties with respect to joint and several liability that may affect the magnitude of the contingency, including disclosure of the aggregate expected cost to remediate particular sites that are individually material if the likelihood of contribution by the other significant parties has not been established. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SiteContingencyUncertaintiesFromJointAndSeveralLiability |