Property, Plant and Equipment - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 1,650,680	$ 1,038,496
Accumulated depreciation, depletion and amortization	(526,370)	(426,842)
Construction in progress	28,760	18,270
Total property, plant and equipment, net	1,153,070	629,924
Construction equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	766,914	570,044
Plants
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	413,983	255,214
Land and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	202,120	94,182
Mineral reserves
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	201,440	69,334
Buildings
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	54,583	39,838
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	10,209	8,616
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 1,431	$ 1,268