Details for Selection
| Standard label: | Revenue, Coal Services |
| Name: | us-gaap:RevenueCoalServices |
| Documentation: | Revenue from services rendered related to coal (mine services, transportation, and others) during the reporting period. |
| Commentary: | |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For period (duration) |
| Balance type: | Credit |
| Object class: | [Concept] |