Details for Selection
| Standard label: | Increase (Decrease) in Coal Inventories |
| Name: | us-gaap:IncreaseDecreaseInCoalInventories |
| Documentation: | The increase (decrease) during the reporting period in the value of coal held in inventory. |
| Commentary: | |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For period (duration) |
| Balance type: | Credit |
| Object class: | [Concept] |