Operating Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues	$ 2,377,227	$ 2,166,808	$ 1,536,493
Cost of services	1,932,688	1,847,878	1,248,495
Gross profit	444,539	318,930	287,998
Selling, general and administrative expenses	298,625	262,714	202,251
Contingent consideration	277	277	211
Loss (gain) on sale of assets	(14,139)	(69)	(47)
Operating income (loss)	159,776	56,008	85,583
Depreciation and amortization	29,407	25,468	21,914
Capital expenditures	17,667	29,255	7,401
Total assets	981,600	934,709	766,622
Communications [Member]
Segment Reporting Information [Line Items]
Revenues	600,776	559,777	445,968
Cost of services	494,964	490,959	361,197
Gross profit	105,812	68,818	84,771
Selling, general and administrative expenses	54,344	46,717	41,373
Contingent consideration	0	0	0
Loss (gain) on sale of assets	12	12	(4)
Operating income (loss)	51,456	22,089	43,402
Depreciation and amortization	2,215	1,550	1,394
Capital expenditures	2,203	2,004	963
Total assets	205,924	210,875	164,699
Residential [Member]
Segment Reporting Information [Line Items]
Revenues	1,279,504	1,131,414	687,347
Cost of services	1,026,524	928,161	553,546
Gross profit	252,980	203,253	133,801
Selling, general and administrative expenses	169,737	144,100	92,761
Contingent consideration	277	277	211
Loss (gain) on sale of assets	69	20	86
Operating income (loss)	82,897	58,856	40,743
Depreciation and amortization	19,281	15,617	11,490
Capital expenditures	9,114	10,054	2,829
Total assets	386,829	394,757	329,691
Infrastructure Solutions [Member]
Segment Reporting Information [Line Items]
Revenues	217,353	167,113	146,980
Cost of services	162,905	138,444	106,048
Gross profit	54,448	28,669	40,932
Selling, general and administrative expenses	26,260	25,129	23,966
Contingent consideration	0	0	0
Loss (gain) on sale of assets	(1,029)	(46)	(10)
Operating income (loss)	29,217	3,586	16,976
Depreciation and amortization	5,198	5,575	6,170
Capital expenditures	2,767	14,729	2,067
Total assets	180,871	161,828	137,628
Commercial and Industrial [Member]
Segment Reporting Information [Line Items]
Revenues	279,594	308,504	256,198
Cost of services	248,295	290,314	227,704
Gross profit	31,299	18,190	28,494
Selling, general and administrative expenses	25,225	30,557	28,172
Contingent consideration	0	0	0
Loss (gain) on sale of assets	(13,198)	(55)	(92)
Operating income (loss)	19,272	(12,312)	414
Depreciation and amortization	1,640	2,561	2,709
Capital expenditures	2,525	1,890	1,453
Total assets	87,677	114,529	87,577
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Revenues	0	0	0
Cost of services	0	0	0
Gross profit	0	0	0
Selling, general and administrative expenses	23,059	16,211	15,979
Contingent consideration	0	0	0
Loss (gain) on sale of assets	7	0	(27)
Operating income (loss)	(23,066)	(16,211)	(15,952)
Depreciation and amortization	1,073	165	151
Capital expenditures	1,058	578	89
Total assets	$ 120,299	$ 52,720	$ 47,027