Operating Segments (Tables)

6 Months Ended

Mar. 31, 2020

Segment Reporting [Abstract]

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

		Three Months Ended March 31, 2020
		Commercial & Industrial		Communications		Infrastructure Solutions		Residential		Corporate		Total
Revenues		$	65,960	$	95,990	$	29,300	$	100,027	$	—	$	291,277
Cost of services		61,492		79,352		22,055		77,114		—		240,013
Gross profit		4,468		16,638		7,245		22,913		—		51,264
Selling, general and administrative		8,586		9,419		4,918		15,754		3,359		42,036
Loss (gain) on sale of assets		(1)		—		—		—		—		(1)
Operating income (loss)		(4,117)		7,219		2,327		7,159		(3,359)		9,229
Other data:
	Depreciation and amortization expense	$	689	$	343	$	1,754	$	431	$	18	$	3,235
	Capital expenditures	$	212	$	186	$	153	$	657	$	299	$	1,507
	Total assets	$	75,075	$	126,871	$	127,426	$	101,246	$	95,726	$	526,344

		Three Months Ended March 31, 2019
		Commercial & Industrial		Communications		Infrastructure Solutions		Residential		Corporate		Total
Revenues		$	79,975	$	70,437	$	34,450	$	72,052	$	—	$	256,914
Cost of services		71,184		58,492		27,004		56,999		—		213,679
Gross profit		8,791		11,945		7,446		15,053		—		43,235
Selling, general and administrative		7,363		7,666		4,685		11,187		4,169		35,070
Contingent consideration		—		—		(149)		—		—		(149)
Loss (gain) on sale of assets		(1)		—		101		(2)		—		98
Operating income (loss)		1,429		4,279		2,809		3,868		(4,169)		8,216
Other data:
	Depreciation and amortization expense	$	629	$	426	$	1,175	$	217	$	27	$	2,474
	Capital expenditures	$	615	$	193	$	635	$	398	$	—	$	1,841
	Total assets	$	77,898	$	91,960	$	114,739	$	55,417	$	77,257	$	417,271

		Six Months Ended March 31, 2020
			Commercial & Industrial		Communications		Infrastructure Solutions		Residential		Corporate		Total
Revenues			$	133,703	$	180,279	$	60,583	$	192,755	$	—	$	567,320
Cost of services			122,500		148,074		45,568		149,699		—		465,841
Gross profit			11,203		32,205		15,015		43,056		—		101,479
Selling, general and administrative			15,874		17,988		9,411		29,474		7,161		79,908
Loss (gain) on sale of assets			(28)		(9)		—		—		—		(37)
Operating income (loss)			(4,643)		14,226		5,604		13,582		(7,161)		21,608
Other data:
	Depreciation and amortization expense		$	1,365	$	680	$	2,874	$	641	$	37	$	5,597
	Capital expenditures		$	672	$	468	$	590	$	869	$	299	$	2,898
	Total assets		$	75,075	$	126,871	$	127,426	$	101,246	$	95,726	$	526,344

		Six Months Ended March 31, 2019
			Commercial & Industrial		Communications		Infrastructure Solutions		Residential		Corporate		Total
Revenues			$	152,558	$	139,762	$	63,929	$	144,507	$	—	$	500,756
Cost of services			135,092		115,851		50,556		114,421		—		415,920
Gross profit			17,466		23,911		13,373		30,086		—		84,836
Selling, general and administrative			14,079		14,600		9,166		22,324		6,987		67,156
Contingent consideration			—		—		(115)		—		—		(115)
Loss (gain) on sale of assets			(4)		—		101		(2)		—		95
Operating income (loss)			3,391		9,311		4,221		7,764		(6,987)		17,700
Other data:
	Depreciation and amortization expense		$	1,255	$	841	$	2,269	$	426	$	55	$	4,846
	Capital expenditures		$	1,467	$	693	$	822	$	845	$	102	$	3,929
	Total assets		$	77,898	$	91,960	$	114,739	$	55,417	$	77,257	$	417,271