Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023
Revenue Recognition and Deferred Revenue [Abstract]
Unbilled Receivables, Current	$ 5,347
Costs and estimated earnings in excess of billings	40,646		$ 48,620
Billings in excess of costs and estimated earnings	(126,962)		$ (103,771)
Contract with Customer, Liability, Revenue Recognized	77,964	$ 38,047
Performance Obligation Next 12 Months	872,321
Revenue, Remaining Performance Obligation, Amount	1,072,593
Disaggregation of Revenue [Line Items]
Revenues	634,444	574,874
Contract with Customer, Liability, Revenue Recognized	77,964	38,047
Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	84,952	60,267
Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	170,748	147,245
Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	62,888	49,284
Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	315,856	318,078
Fixed-price Contract [Member]
Disaggregation of Revenue [Line Items]
Revenues	575,869	504,793
Fixed-price Contract [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	73,910	51,895
Fixed-price Contract [Member] | Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	125,223	87,274
Fixed-price Contract [Member] | Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	60,880	47,546
Fixed-price Contract [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	315,856	318,078
Time-and-materials Contract [Member]
Disaggregation of Revenue [Line Items]
Revenues	58,575	70,081
Time-and-materials Contract [Member] | Commercial and Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues	11,042	8,372
Time-and-materials Contract [Member] | Communications [Member]
Disaggregation of Revenue [Line Items]
Revenues	45,525	59,971
Time-and-materials Contract [Member] | Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,008	1,738
Time-and-materials Contract [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0
industrial Services [Member] | Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	11,098	10,955
Custom Power Solutions [Member] | Infrastructure Solutions [Member]
Disaggregation of Revenue [Line Items]
Revenues	51,790	38,329
Single Family Contracts [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	246,567	243,710
Multi Family and Other [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 69,289	$ 74,368