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Revenue from contracts with customers - Disaggregation of revenue (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2024 | Jun. 30, 2023 | Jun. 30, 2024 | Jun. 30, 2023
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | $ 1,035,762 | $ 1,079,031 | $ 2,240,111 | $ 2,501,913
Other revenues | 11,783 | 12,095 | 21,259 | 19,311
Total external operating revenues | 1,047,545 | 1,091,126 | 2,261,370 | 2,521,224
Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (10,833) | (11,165) | (42,732) | (39,105)
Total external operating revenues | (10,833) | (11,165) | (42,732) | (39,105)
Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total external operating revenues | 1,056,960 | 1,099,140 | 2,301,252 | 2,555,606
Natural gas transportation |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 56,730 | 46,065 | 114,958 | 94,553
Natural gas storage |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 5,331 | 3,758 | 10,713 | 7,620
Electrical & mechanical specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 502,015 | 568,307 | 941,393 | 1,158,570
Transmission & distribution specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 190,881 | 167,485 | 367,741 | 319,507
Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 24,526 | 22,068 | 47,092 | 42,132
Residential utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 138,127 | 151,792 | 440,452 | 517,267
Commercial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 105,894 | 109,458 | 309,539 | 350,731
Industrial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 21,026 | 19,553 | 46,954 | 47,154
Other utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 2,065 | 1,710 | 4,001 | 3,484
Electric | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (64) | (27) | (93) | (55)
Electric | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 100,002 | 92,671 | 209,625 | 191,231
Other revenues | (845) | (1,682) | (2,742) | (4,545)
Total external operating revenues | 99,157 | 90,989 | 206,883 | 186,686
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 | 13,186 | 11,531 | 28,816 | 23,410
Electric | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 31,437 | 30,825 | 70,659 | 68,650
Electric | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 41,620 | 38,262 | 83,135 | 74,609
Electric | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 11,758 | 10,370 | 23,107 | 21,133
Electric | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 2,065 | 1,710 | 4,001 | 3,484
Natural gas distribution | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (49) | (69) | (105) | (139)
Natural gas distribution | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 199,274 | 216,220 | 656,823 | 783,789
Other revenues | 2,157 | 2,775 | 4,078 | 801
Total external operating revenues | 201,431 | 218,995 | 660,901 | 784,590
Natural gas distribution | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 13,324 | 11,671 | 27,915 | 25,175
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 | 5,767 | 3,272 | 8,969 | 7,993
Natural gas distribution | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 106,690 | 120,967 | 369,793 | 448,617
Natural gas distribution | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 64,274 | 71,196 | 226,404 | 276,122
Natural gas distribution | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 9,268 | 9,183 | 23,847 | 26,021
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 | (9,055) | (7,918) | (39,365) | (34,188)
Pipeline | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 43,792 | 34,171 | 64,757 | 48,607
Other revenues | 39 | 38 | 86 | 76
Total external operating revenues | 43,831 | 34,209 | 64,843 | 48,683
Pipeline | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 43,406 | 34,394 | 87,043 | 69,378
Pipeline | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 5,331 | 3,758 | 10,713 | 7,620
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 | 4,110 | 3,937 | 6,366 | 5,797
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 | (249) | 0 | (336) | 0
Construction services | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 692,692 | 735,969 | 1,308,889 | 1,478,286
Other revenues | 10,432 | 10,964 | 19,837 | 22,979
Total external operating revenues | 703,124 | 746,933 | 1,328,726 | 1,501,265
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 | 502,015 | 568,307 | 941,393 | 1,158,570
Construction services | Transmission & distribution specialty contracting | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 190,881 | 167,485 | 367,741 | 319,507
Construction services | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 45 | 177 | 91 | 209
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 | (1,416) | (3,151) | (2,833) | (4,723)
Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 2 | 0 | 17 | 0
Other revenues | 0 | 0 | 0 | 0
Total external operating revenues | 2 | 0 | 17 | 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 | 1,418 | 3,151 | 2,850 | 4,723
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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