cm:Concept: us-gaap:AssetRetirementObligationLiabilitiesSettled
| Asset Retirement Obligation, Liabilities Settled |
| us-gaap:AssetRetirementObligationLiabilitiesSettled |
| Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:AssetRetirementObligationLiabilitiesSettled |