XML 89 R9.htm IDEA: XBRL DOCUMENT
v3.25.1

OTHER LONG-TERM ASSETS (IN THOUSANDS) | 12 Months Ended
--- | ---
Dec. 31, 2024
OTHER LONG-TERM ASSETS (IN THOUSANDS) |
OTHER LONG-TERM ASSETS (IN THOUSANDS) | (3) OTHER LONG-TERM ASSETS (IN THOUSANDS) ​
​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | December 31,
​ |  | 2024 |  | 2023
Advanced coal royalties | ​ | $ | 3,906 | ​ | $ | 5,521
Other | ​ |  | 45 | ​ |  | —
Total other assets | ​ | $ | 3,951 | ​ | $ | 5,521
​

X
- Definition The entire disclosure for other assets. This disclosure includes other current assets and other noncurrent assets. + References No definition available. + Details
Name: | us-gaap_OtherAssetsDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_OtherAssetsNoncurrentDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration