v3.26.1
Revenue Recognition (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Sep. 30, 2025
Revenue Recognition and Deferred Revenue [Abstract]          
Unbilled Receivables, Current $ 22,344   $ 22,344    
Costs and estimated earnings in excess of billings 100,850   100,850   $ 69,229
Billings in excess of costs and estimated earnings (286,548)   (286,548)   $ (176,782)
Contract with Customer, Liability, Revenue Recognized     154,185 $ 140,390  
Performance Obligation Next 12 Months 1,839,240   1,839,240    
Revenue, Remaining Performance Obligation, Amount 2,347,101   2,347,101    
Disaggregation of Revenue [Line Items]          
Revenues 974,284 $ 833,960 1,845,242 1,583,507  
Contract with Customer, Liability, Revenue Recognized     154,185 140,390  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]          
Performance Obligation Next 12 Months 1,839,240   1,839,240    
Revenue, Remaining Performance Obligation, Amount 2,347,101   2,347,101    
Commercial and Industrial [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 126,524 125,358 221,343 213,849  
Communications [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 367,696 273,016 719,616 505,976  
Infrastructure Solutions [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 192,448 117,620 332,623 225,745  
Residential [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 287,616 317,966 571,660 637,937  
Fixed-price Contract [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 783,351 734,371 1,506,190 1,397,065  
Fixed-price Contract [Member] | Commercial and Industrial [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 112,454 107,516 196,045 183,706  
Fixed-price Contract [Member] | Communications [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 219,657 202,412 443,351 368,745  
Fixed-price Contract [Member] | Infrastructure Solutions [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 163,624 106,477 295,134 206,677  
Fixed-price Contract [Member] | Residential [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 287,616 317,966 571,660 637,937  
Time-and-materials Contract [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 190,933 99,589 339,052 186,442  
Time-and-materials Contract [Member] | Commercial and Industrial [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 14,070 17,842 25,298 30,143  
Time-and-materials Contract [Member] | Communications [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 148,039 70,604 276,265 137,231  
Time-and-materials Contract [Member] | Infrastructure Solutions [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 28,824 11,143 37,489 19,068  
Time-and-materials Contract [Member] | Residential [Member]          
Disaggregation of Revenue [Line Items]          
Revenues $ 0 0 $ 0 0  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01          
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]          
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 12 months   12 months    
industrial Services [Member] | Infrastructure Solutions [Member]          
Disaggregation of Revenue [Line Items]          
Revenues $ 40,687 29,178 $ 64,878 47,846  
Custom Power Solutions [Member] | Infrastructure Solutions [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 151,761 88,442 267,745 177,899  
Single Family Contracts [Member] | Residential [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 134,202 160,065 271,181 329,282  
Multi Family and Other [Member] | Residential [Member]          
Disaggregation of Revenue [Line Items]          
Revenues 63,355 78,733 127,560 155,304  
Single Family Contracts Plumbing HVAC | Residential [Member]          
Disaggregation of Revenue [Line Items]          
Revenues $ 90,059 $ 79,168 $ 172,919 $ 153,351