v3.26.1
Property, Plant and Equipment (Schedule of Property, Plant and Equipment) (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment $ 2,999,563 $ 2,951,214
Less accumulated depreciation, depletion, amortization and impairment 1,508,186 1,296,759
Property, plant and equipment, net 1,491,377 1,654,455
Land [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment 29,301 29,008
Buildings And Improvements [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment 141,699 138,771
Plant, Machinery, Mining Equipment And Transportation Vehicles [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment 1,543,353 1,516,095
Mineral Rights And Reserves [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment 370,393 370,393
Office And Computer Equipment [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment 20,442 20,063
Mine Development [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment 708,119 694,779
Asset Retirement Obligation Asset [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment 80,502 79,094
Construction In Process [Member]    
Property Plant And Equipment [Line Items]    
Total cost of property, plant and equipment $ 105,754 $ 103,011