Revenue from Contracts with Customers - Schedule of the Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation of Revenue [Line Items]
Operating revenue	$ 760,985	$ 717,406	$ 2,090,047	$ 2,218,672
Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	765,399	721,361	2,105,555	2,229,661
Eliminations
Disaggregation of Revenue [Line Items]
Operating revenue	(4,414)	(3,955)	(15,508)	(10,989)
Fixed-price | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	433,908	364,649	1,248,617	1,045,791
Unit-price | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	61,879	47,991	167,270	124,889
Cost reimbursable | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	269,612	308,721	689,668	1,058,981
Electrical & Mechanical
Disaggregation of Revenue [Line Items]
Operating revenue	534,741	514,378	1,476,151	1,672,948
Electrical & Mechanical | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	536,895	516,933	1,481,778	1,680,210
Electrical & Mechanical | Eliminations
Disaggregation of Revenue [Line Items]
Operating revenue	(2,154)	(2,555)	(5,627)	(7,262)
Electrical & Mechanical | Commercial | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	327,403	266,587	860,088	947,792
Electrical & Mechanical | Industrial | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	76,493	116,013	236,349	367,331
Electrical & Mechanical | Institutional | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	93,390	76,276	274,916	195,178
Electrical & Mechanical | Renewables | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	10,414	19,244	27,551	43,947
Electrical & Mechanical | Service & other | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	29,195	38,813	82,874	125,962
Electrical & Mechanical | Fixed-price | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	326,972	272,042	966,035	784,334
Electrical & Mechanical | Unit-price | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	15,031	18,401	49,254	62,488
Electrical & Mechanical | Cost reimbursable | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	194,892	226,490	466,489	833,388
Transmission & Distribution
Disaggregation of Revenue [Line Items]
Operating revenue	226,244	203,028	613,896	545,724
Transmission & Distribution | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	228,504	204,428	623,777	549,451
Transmission & Distribution | Eliminations
Disaggregation of Revenue [Line Items]
Operating revenue	(2,260)	(1,400)	(9,881)	(3,727)
Transmission & Distribution | Utility | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	206,669	188,680	559,922	508,850
Transmission & Distribution | Transportation | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	21,835	15,748	63,855	40,601
Transmission & Distribution | Fixed-price | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	106,936	92,607	282,582	261,457
Transmission & Distribution | Unit-price | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	46,848	29,590	118,016	62,401
Transmission & Distribution | Cost reimbursable | Operating segments
Disaggregation of Revenue [Line Items]
Operating revenue	$ 74,720	$ 82,231	$ 223,179	$ 225,593