Significant Accounting Policies (Tables)

12 Months Ended

Sep. 30, 2020

Accounting Policies [Abstract]

Schedule of customer concentration risk

Customers that accounted for more than 10.0% of consolidated revenues during either of those periods are presented below:

	% of Consolidated Revenues for the Fiscal Year Ended September 30,
	2020		2019
Alabama Department of Transportation	11.6	%	13.8	%
North Carolina Department of Transportation	7.8	%	13.1	%

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,
	2020	2019
Public	65.3%	69.3%
Private	34.7%	30.7%

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
Quarry 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, 2020 and 2019 consisted of the following (in thousands):

	September 30,
	2020		2019
Construction equipment	$	253,157	$	214,500
Plants	102,392		92,279
Land and improvements	40,614		34,365
Quarry reserves	20,238		20,678
Buildings	18,307		15,458
Furniture and fixtures	5,648		4,864
Leasehold improvements	1,135		1,135
Total property, plant and equipment, gross	441,491		383,279
Accumulated depreciation, depletion and amortization	(209,532)		(177,927)
Construction in progress	5,271		518
Total property, plant and equipment, net	$	237,230	$	205,870