| Standard label: | Asset Retirement Obligation |
| Name: | us-gaap:AssetRetirementObligation |
| Documentation: | 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. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Credit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:AssetRetirementObligation |
| Label | Role | Language |
| Asset Retirement Obligation | http://www.xbrl.org/2003/role/label | en-US |
| Asset Retirement Obligation, Ending Balance | http://www.xbrl.org/2003/role/periodEndLabel | en-US |
| Asset Retirement Obligation, Beginning Balance | http://www.xbrl.org/2003/role/periodStartLabel | en-US |
| Asset Retirement Obligation, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 410 20 50 1 (c) | http://fasb.org/us-gaap/role/ref/legacyRef | 410 |