Revenue Recognition (Tables)

12 Months Ended

Sep. 30, 2019

Revenue Recognition and Deferred Revenue [Abstract]

Disaggregation of Revenue [Table Text Block]

	Year Ended September 30,
	2019		2018		2017
Commercial & Industrial	$	305,624	$	274,299	$	227,606
Communications	321,246		219,655		225,275
Infrastructure Solutions
Industrial Services	48,948		44,701		46,079
Custom Power Solutions	87,842		52,462		37,745
Total Infrastructure Solutions	136,790		97,163		83,824
Residential
Single-family	212,358		190,379		162,100
Multi-family and Other	100,978		95,332		111,939
Total Residential	313,336		285,711		274,039
Total Revenue	$	1,076,996	$	876,828	$	810,744

	Year Ended September 30, 2019
		Commercial & Industrial		Communications		Infrastructure Solutions		Residential		Total
Fixed-price		$	286,319	$	229,143	$	129,096	$	313,336	$	957,894
Time-and-material			19,305		92,103		7,694		—		119,102
Total revenue		$	305,624	$	321,246	$	136,790	$	313,336	$	1,076,996
	Year Ended September 30, 2018
		Commercial & Industrial		Communications		Infrastructure Solutions		Residential		Total
Fixed-price		$	244,464	$	166,258	$	90,155	$	285,711	$	786,588
Time-and-material			29,835		53,397		7,008		—		90,240
Total revenue		$	274,299	$	219,655	$	97,163	$	285,711	$	876,828
	Year Ended September 30, 2017
		Commercial & Industrial		Communications		Infrastructure Solutions		Residential		Total
Fixed-price		$	206,850	$	174,922	$	76,232	$	274,039	$	732,043
Time-and-material			20,756		50,353		7,592		—		78,701
Total revenue		$	227,606	$	225,275	$	83,824	$	274,039	$	810,744

Contract with Customer, Asset and Liability [Table Text Block]

The net asset (liability) position for contracts in process consisted of the following:

	September 30,
	2019			2018
Costs and estimated earnings on uncompleted contracts	$	761,401		$	539,226
Less: Billings to date and unbilled accounts receivable		(772,104	)		(541,606	)
	$	(10,703	)	$	(2,380	)

The net asset (liability) position for contracts in process included in the accompanying consolidated balance sheets was as follows:

	September 30,
	2019			2018
Costs and estimated earnings in excess of billings	$	29,860		$	31,446
Billings in excess of costs and estimated earnings		(40,563	)		(33,826	)
	$	(10,703	)	$	(2,380	)