Significant Accounting Policies (Tables)

12 Months Ended

Sep. 30, 2022

Accounting Policies [Abstract]

Schedule of customer concentration risk

Customers that accounted for more than 10% of consolidated revenues during any of the fiscal years ended September 30, 2022, 2021 and 2020 are presented below:

	% of Consolidated Revenues for the Fiscal Year Ended September 30,
	2022	2021	2020
Alabama Department of Transportation	10.0%	10.8%	11.6%
North Carolina Department of Transportation	11.2%	10.3%	7.8%

Schedule of revenue by major customers by reporting segments

The following table reflects, for the periods presented, (i) revenues generated from public infrastructure construction projects and the sale of construction materials to public customers and (ii) revenues generated from private infrastructure construction projects and the sale of construction materials to private customers.

	% of Consolidated Revenues for the Fiscal Year Ended September 30,
	2022	2021	2020
Public	60.9%	61.3%	65.3%
Private	39.1%	38.7%	34.7%

Schedule of useful lives of property, plant and equipment

The estimated useful lives of property, plant and equipment categories are as follows:

Category	Estimated Useful Life
Land and improvements	Land, unlimited; improvements, 15-25 years
Mineral reserves	Based on depletion
Buildings	5 - 39 years
Plants	3 - 20 years
Construction equipment	3 - 10 years
Furniture and fixtures	5 - 10 years
Leasehold improvements	The shorter of 15 years or the remaining lease term

Property, plant and equipment at September 30, 2022 and 2021 consisted of the following (in thousands):

	September 30,
	2022		2021
Construction equipment	$	402,581	$	333,966
Plants	167,625		143,172
Land and improvements	59,454		53,415
Mineral reserves	91,992		86,556
Buildings	32,566		27,163
Furniture and fixtures	7,110		6,426
Leasehold improvements	1,230		1,230
Total property, plant and equipment, gross	762,558		651,928
Accumulated depreciation, depletion and amortization	(304,935)		(250,803)
Construction in progress	23,789		3,707
Total property, plant and equipment, net	$	481,412	$	404,832