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Revenue from contracts with customers - Schedule of 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] |  |  |  |
Revenues from contracts with customers | $ 1,041,392 | $ 991,276 | $ 3,281,504 | $ 3,493,191
Other revenues | 9,124 | 9,519 | 30,382 | 28,829
Total external operating revenues | 1,050,516 | 1,000,795 | 3,311,886 | 3,522,020
Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (5,563) | (5,486) | (48,294) | (44,591)
Total external operating revenues | (5,563) | (5,486) | (48,294) | (44,591)
Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total external operating revenues | 1,054,646 | 1,004,592 | 3,355,897 | 3,560,199
Natural gas transportation |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 57,215 | 48,388 | 172,173 | 142,941
Natural gas storage |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 6,053 | 4,808 | 16,766 | 12,427
Electrical & mechanical specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 534,613 | 514,378 | 1,476,006 | 1,672,948
Transmission & distribution specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 216,062 | 192,056 | 583,803 | 511,563
Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 31,057 | 24,098 | 78,149 | 66,231
Residential utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 99,004 | 103,036 | 539,456 | 620,304
Commercial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 84,335 | 90,114 | 393,874 | 440,846
Industrial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 16,571 | 18,019 | 63,525 | 65,173
Other utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 2,045 | 1,865 | 6,046 | 5,349
Electric | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (96) | (27) | (188) | (82)
Electric | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 111,557 | 111,343 | 321,183 | 302,574
Other revenues | (3,173) | (3,254) | (5,915) | (7,799)
Total external operating revenues | 108,384 | 108,089 | 315,268 | 294,775
Electric | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Electric | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Electric | Electrical & mechanical specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Electric | Transmission & distribution specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Electric | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 16,182 | 14,701 | 44,998 | 38,111
Electric | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 37,076 | 34,303 | 107,735 | 102,953
Electric | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 46,648 | 49,754 | 129,783 | 124,363
Electric | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 9,702 | 10,747 | 32,809 | 31,880
Electric | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 2,045 | 1,865 | 6,046 | 5,349
Natural gas distribution | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (104) | (69) | (209) | (208)
Natural gas distribution | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 131,395 | 133,227 | 788,218 | 917,018
Other revenues | 2,122 | 1,669 | 6,200 | 2,469
Total external operating revenues | 133,517 | 134,896 | 794,418 | 919,487
Natural gas distribution | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 15,279 | 13,050 | 43,194 | 38,225
Natural gas distribution | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Natural gas distribution | Electrical & mechanical specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Natural gas distribution | Transmission & distribution specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Natural gas distribution | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 9,736 | 3,881 | 18,705 | 11,874
Natural gas distribution | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 61,928 | 68,733 | 431,721 | 517,351
Natural gas distribution | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 37,687 | 40,360 | 264,091 | 316,483
Natural gas distribution | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 6,869 | 7,272 | 30,716 | 33,293
Natural gas distribution | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Pipeline | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (3,931) | (3,701) | (43,296) | (37,889)
Pipeline | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 47,595 | 40,361 | 112,352 | 88,967
Other revenues | 33 | 43 | 119 | 119
Total external operating revenues | 47,628 | 40,404 | 112,471 | 89,086
Pipeline | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 41,936 | 35,338 | 128,979 | 104,716
Pipeline | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 6,053 | 4,808 | 16,766 | 12,427
Pipeline | Electrical & mechanical specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Pipeline | Transmission & distribution specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Pipeline | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 3,537 | 3,916 | 9,903 | 9,713
Pipeline | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Pipeline | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Pipeline | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Pipeline | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Construction services | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | (336) | 0
Construction services | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 750,844 | 706,345 | 2,059,733 | 2,184,632
Other revenues | 10,142 | 11,061 | 29,978 | 34,040
Total external operating revenues | 760,986 | 717,406 | 2,089,711 | 2,218,672
Construction services | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Construction services | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Construction services | Electrical & mechanical specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 534,613 | 514,378 | 1,476,006 | 1,672,948
Construction services | Transmission & distribution specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 216,062 | 192,056 | 583,803 | 511,563
Construction services | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 169 | (89) | 260 | 121
Construction services | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Construction services | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Construction services | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Construction services | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (1,432) | (1,689) | (4,265) | (6,412)
Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 1 | 0 | 18 | 0
Other revenues | 0 | 0 | 0 | 0
Total external operating revenues | 1 | 0 | 18 | 0
Other | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Electrical & mechanical specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Transmission & distribution specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 1,433 | 1,689 | 4,283 | 6,412
Other | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 | 0 | 0
Other | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | $ 0 | $ 0 | $ 0 | $ 0

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