XML 151 R68.htm IDEA: XBRL DOCUMENT v3.25.0.1
Fair Value Disclosure (Narrative) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Gain on equity securities $ 1,805 $ 1,958  
Business interruption insurance recoveries 13,612 0  
Long-term debt 99,430 35,800  
Fair Value, Nonrecurring | MLMC      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Non-cash asset impairment charge   65,900  
Fair Value, Nonrecurring | Coal Mining      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Non-cash asset impairment charge   60,800  
Fair Value, Nonrecurring | Mineral Management      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Non-cash asset impairment charge   5,100  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Gain on equity securities 300 400  
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Reported Value Measurement      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Equity securities cost     $ 2,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Bellaire      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Gain on equity securities 1,500 1,600  
Significant Other Observable Inputs (Level 2)      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Long-term debt fair value $ 97,900 $ 35,300