| Standard label: | Coal Industry Retiree Health Benefit Act of 1992, Impact, Description |
| Name: | us-gaap:CoalIndustryRetireeHealthBenefitActOf1992ImpactOfAct |
| Documentation: | Description of impact of providing medical and death benefits under Coal Industry Retiree Health Benefit Act of 1992. |
| Object type: | cm:Concept |
| Data type: | Text/String (xbrli:stringItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:CoalIndustryRetireeHealthBenefitActOf1992ImpactOfAct |
| Label | Role | Language |
| Coal Industry Retiree Health Benefit Act of 1992, Impact, Description | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 930 715 50 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 930 |