v3.26.1
Unconsolidated Subsidiaries (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Variable Interest Entity [Line Items]      
Variable interest entity, reporting entity involvement, maximum risk of loss $ 5,600   $ 6,700
Earnings of unconsolidated operations 16,571 $ 15,986  
Utility Coal Mining and Contract Mining Member      
Variable Interest Entity [Line Items]      
Earnings of unconsolidated operations $ 15,600 $ 15,400  
Unconsolidated Subsidiaries      
Variable Interest Entity [Line Items]      
Ownership (percent) 100.00%    
Income from equity method investee $ 15,513   14,750
Other Noncurrent Assets      
Variable Interest Entity [Line Items]      
Income from equity method investee $ 15,500   $ 14,800