cm:Concept: us-gaap:SiteContingencyLossExposureNotAccruedThirdPartyRecoveryCommentary
| Site Contingency, Loss Exposure Not Accrued, Third Party Recovery Commentary |
| us-gaap:SiteContingencyLossExposureNotAccruedThirdPartyRecoveryCommentary |
| Describes the extent to which disclosed but not recognized contingent remediation losses are expected to be recoverable through insurance, indemnification arrangements, or other sources, and any material limitations of that recovery. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SiteContingencyLossExposureNotAccruedThirdPartyRecoveryCommentary |