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Property, Plant and Equipment, Net - Schedule of Net Property, Plant and Equipment (Detail) - USD ($)
$ in Thousands
Mar. 31, 2024
Dec. 31, 2023
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross $ 417,436 $ 414,230
Less: accumulated depreciation and depletion 166,052 159,138
Total property, plant and equipment, net 251,384 255,092
Machinery, equipment and tooling    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 41,748 40,632
SmartSystems    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 31,127 30,651
Vehicles    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 4,240 4,082
Furniture and fixtures    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 1,466 1,466
Plant and building    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 215,098 213,756
Real estate properties    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 7,209 7,209
Railroad and sidings    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 35,719 35,491
Land and land improvements    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 40,528 40,519
Asset retirement obligations    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 22,910 22,910
Mineral properties    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 7,442 7,442
Deferred mining costs    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross 4,207 3,802
Construction in progress    
Property, Plant and Equipment [Line Items]    
Property, plant and equipment, gross $ 5,742 $ 6,270