cm:Concept: us-gaap:AccrualForEnvironmentalLossContingenciesMaterialComponents
| Accrual for Environmental Loss Contingencies, Material Components |
| us-gaap:AccrualForEnvironmentalLossContingenciesMaterialComponents |
| Description of the material components comprising environmental loss contingencies, which arose from improper operations by the current or prior site owner or operator. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:AccrualForEnvironmentalLossContingenciesMaterialComponents |