cm:Concept: us-gaap:AssetRetirementObligationsNoncurrent
| Asset Retirement Obligations, Noncurrent |
| us-gaap:AssetRetirementObligationsNoncurrent |
| Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:AssetRetirementObligationsNoncurrent |