Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 4,657,340	$ 4,441,784	$ 3,454,436
Other revenues	42,883	40,520	52,245
Total external operating revenues	4,614,457	4,401,264	3,402,191
Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	4,720,713	4,505,706	3,515,695
Intersegment eliminations
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	(71,314)	(69,762)	(65,865)
Total external operating revenues	(71,314)	(69,762)	(65,865)
Natural gas transportation
Disaggregation of Revenue [Line Items]
Total external operating revenues	197,762	178,176	162,409
Natural gas storage
Disaggregation of Revenue [Line Items]
Total external operating revenues	18,254	14,583	14,680
Electrical & mechanical specialty contracting
Disaggregation of Revenue [Line Items]
Total external operating revenues	2,125,536	1,988,729	1,324,419
Transmission & distribution specialty contracting
Disaggregation of Revenue [Line Items]
Total external operating revenues	683,342	662,705	677,074
Other
Disaggregation of Revenue [Line Items]
Total external operating revenues	91,637	76,951	72,299
Residential utility sales
Disaggregation of Revenue [Line Items]
Total external operating revenues	860,874	856,825	671,562
Commercial utility sales
Disaggregation of Revenue [Line Items]
Total external operating revenues	612,828	599,984	465,841
Industrial utility sales
Disaggregation of Revenue [Line Items]
Total external operating revenues	88,268	85,476	72,721
Other utility sales
Disaggregation of Revenue [Line Items]
Total external operating revenues	7,270	7,597	7,051
Electric | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	400,901	376,936	349,412
Other revenues	(10,261)	(4,714)	(6,525)
Total external operating revenues	411,162	381,650	355,937
Electric | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Total external operating revenues	(274)	(137)	(170)
Electric | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Electric | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Electric | Electrical & mechanical specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Electric | Transmission & distribution specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Electric | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	54,508	45,608	42,902
Electric | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	136,274	138,634	126,841
Electric | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	170,321	146,182	137,556
Electric | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	43,063	43,766	41,757
Electric | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	7,270	7,597	7,051
Natural gas distribution | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,287,121	1,273,530	971,640
Other revenues	7,619	(2,402)	8,995
Total external operating revenues	1,279,502	1,275,932	962,645
Natural gas distribution | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Total external operating revenues	(416)	(274)	(300)
Natural gas distribution | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	52,465	48,886	48,408
Natural gas distribution | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Natural gas distribution | Electrical & mechanical specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Natural gas distribution | Transmission & distribution specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Natural gas distribution | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	15,141	13,617	10,567
Natural gas distribution | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	724,600	718,191	544,721
Natural gas distribution | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	442,507	453,802	328,285
Natural gas distribution | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	45,205	41,710	30,964
Natural gas distribution | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Pipeline | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	115,072	96,695	83,066
Other revenues	187	256	188
Total external operating revenues	114,885	96,439	82,878
Pipeline | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Total external operating revenues	(62,540)	(58,884)	(59,470)
Pipeline | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	145,297	129,290	114,001
Pipeline | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	18,254	14,583	14,680
Pipeline | Electrical & mechanical specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Pipeline | Transmission & distribution specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Pipeline | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	13,874	11,450	13,667
Pipeline | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Pipeline | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Pipeline | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Pipeline | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Construction services | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	2,854,246	2,694,623	2,050,234
Other revenues	45,338	47,380	49,587
Total external operating revenues	2,808,908	2,647,243	2,000,647
Construction services | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Total external operating revenues	(143)	(4,627)	(1,403)
Construction services | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Construction services | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Construction services | Electrical & mechanical specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	2,125,536	1,988,729	1,324,419
Construction services | Transmission & distribution specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	683,342	662,705	677,074
Construction services | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	173	436	557
Construction services | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Construction services | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Construction services | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Construction services | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	0	0	84
Other revenues	0	0	0
Total external operating revenues	0	0	84
Other | Intersegment eliminations
Disaggregation of Revenue [Line Items]
Total external operating revenues	(7,941)	(5,840)	(4,522)
Other | Natural gas transportation | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Natural gas storage | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Electrical & mechanical specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Transmission & distribution specialty contracting | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Other | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	7,941	5,840	4,606
Other | Residential utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Commercial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Industrial utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	0	0	0
Other | Other utility sales | Operating Segments
Disaggregation of Revenue [Line Items]
Total external operating revenues	$ 0	$ 0	$ 0