| Standard label: | Schedule of Change in Asset Retirement Obligation [Table Text Block] |
| Name: | us-gaap:ScheduleOfChangeInAssetRetirementObligationTableTextBlock |
| Documentation: | Tabular disclosure of the changes in carrying amount of a liability for asset retirement obligations, for changes such as new obligations, changes in estimates of existing obligations, spending on existing obligations, property dispositions, and foreign currency translation. |
| Object type: | cm:Level3TextBlock |
| Data type: | Text Block (HTML) (nonnum:textBlockItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:ScheduleOfChangeInAssetRetirementObligationTableTextBlock |
| Examples of this text block disclosure: | AssetRetirementObligationRollForwardAnalysisRollForward |
| Label | Role | Language |
| Schedule of Change in Asset Retirement Obligation [Table Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 410 30 50 5 | http://fasb.org/us-gaap/role/ref/legacyRef | 410 |