Operating Segments (Tables)

12 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

		Year Ended September 30, 2019
		Commercial & Industrial			Communications			Infrastructure Solutions			Residential			Corporate			Total
Revenues		$	305,624		$	321,246		$	136,790		$	313,336		$	—		$	1,076,996
Cost of services		275,722			264,746			105,863			248,562			—			894,893
Gross profit		29,902			56,500			30,927			64,774			—			182,103
Selling, general and administrative		27,815			31,850			18,664			46,864			15,382			140,575
Contingent consideration		—			(97		)	(277		)	—			—			(374		)
Loss (gain) on sale of assets		(30		)	(6		)	105			(17		)	—			52
Income (loss) from operations		$	2,117		$	24,753		$	12,435		$	17,927		$	(15,382	)	$	41,850
Other data:
	Depreciation and amortization expense	$	2,563		$	1,513		$	4,528		$	852		$	101		$	9,557
	Capital expenditures	$	2,402		$	973		$	1,377		$	1,412		$	136		$	6,300
	Total assets	$	82,050		$	109,263		$	116,867		$	63,903		$	73,175		$	445,258

		Year Ended September 30, 2018
		Commercial & Industrial			Communications			Infrastructure Solutions		Residential		Corporate			Total
Revenues		$	274,299		$	219,655		$	97,163	$	285,711	$	—		$	876,828
Cost of services		244,656			179,518			75,337		227,355		—			726,866
Gross profit		29,643			40,137			21,826		58,356		—			149,962
Selling, general and administrative		27,031			26,003			18,293		41,401		11,192			123,920
Contingent consideration		(100		)	(85		)	288		—		—			103
Loss (gain) on sale of assets		(37		)	(4		)	18		8		—			(15		)
Income (loss) from operations		$	2,749		$	14,223		$	3,227	$	16,947	$	(11,192	)	$	25,954
Other data:
	Depreciation and amortization expense	$	2,197		$	1,247		$	4,672	$	637	$	107		$	8,860
	Capital expenditures	$	2,216		$	647		$	735	$	932	$	33		$	4,563
	Total assets	$	89,729		$	80,528		$	109,506	$	55,176	$	87,055		$	421,994

		Year Ended September 30, 2017
		Commercial & Industrial			Communications			Infrastructure Solutions			Residential		Corporate			Total
Revenues		$	227,606		$	225,275		$	83,824		$	274,039	$	—		$	810,744
Cost of services		208,619			187,419			63,399			210,809		—			670,246
Gross profit		18,987			37,856			20,425			63,230		—			140,498
Selling, general and administrative		20,170			24,219			17,859			43,689		14,433			120,370
Contingent consideration		—			—			(145		)	—		—			(145		)
Loss (gain) on sale of assets		(32		)	(1		)	(79		)	43		—			(69		)
Income (loss) from operations		$	(1,151	)	$	13,638		$	2,790		$	19,498	$	(14,433	)	$	20,342
Other data:
	Depreciation and amortization expense	$	1,648		$	740		$	6,412		$	565	$	269		$	9,634
	Capital expenditures	$	1,241		$	2,046		$	538		$	561	$	203		$	4,589
	Total assets	$	84,756		$	63,917		$	106,114		$	51,994	$	117,713		$	424,494