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

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- Definition Tabular disclosure of noncurrent assets. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(17)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
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