cm:Concept: us-gaap:EnvironmentalRemediationCostsRecognizedDisclosure
| Environmental Remediation Costs Recognized Disclosure |
| us-gaap:EnvironmentalRemediationCostsRecognizedDisclosure |
| Description of the nature and cause of the charge against earnings for environmental loss contingencies and recoveries from third parties credited to environmental remediation costs. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:EnvironmentalRemediationCostsRecognizedDisclosure |