v3.26.1
Property, Plant and Equipment - Property, Plant and Equipment (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross $ 1,840,978 $ 1,650,680
Accumulated depreciation, depletion and amortization (609,140) (526,370)
Construction in progress 63,854 28,760
Total property, plant and equipment, net 1,295,692 1,153,070
Construction equipment    
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross 851,156 766,914
Plants    
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross 479,083 413,983
Mineral reserves    
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross 201,440 201,440
Land and improvements    
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross 228,624 202,120
Buildings    
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross 69,397 54,583
Furniture and fixtures    
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross 9,658 10,209
Leasehold improvements    
Property, Plant, and Equipment [Line Items]    
Total property, plant and equipment, gross $ 1,620 $ 1,431