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Revenue from contracts with customers - Schedule of Disaggregation of revenue (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | $ 348,678 | $ 343,120 | $ 1,026,697 | $ 931,324
Other revenues | 2,508 | 1,351 | (678) | 1,422
Total external operating revenues | 351,186 | 344,471 | 1,026,019 | 932,746
Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (10,208) | (9,138) | (43,995) | (39,503)
Total external operating revenues | (10,208) | (9,138) | (43,995) | (39,503)
Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Total external operating revenues | 361,215 | 353,587 | 1,069,656 | 972,190
Natural gas transportation |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 61,934 | 56,730 | 128,897 | 114,958
Natural gas storage |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 5,172 | 5,331 | 11,202 | 10,713
Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 33,905 | 23,085 | 76,514 | 44,210
Residential utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 128,610 | 138,127 | 457,530 | 440,452
Commercial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 109,127 | 105,894 | 349,935 | 309,539
Industrial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 18,345 | 21,026 | 42,971 | 46,954
Other utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 1,793 | 2,065 | 3,643 | 4,001
Electric | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (140) | (48) | (318) | (60)
Total external operating revenues | (140) | (48) | (318) | (60)
Electric | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 100,020 | 100,018 | 216,609 | 209,658
Other revenues | (2,134) | (845) | (6,462) | (2,742)
Total external operating revenues | 97,886 | 99,173 | 210,147 | 206,916
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 | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 17,123 | 13,186 | 34,714 | 28,816
Electric | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 28,569 | 31,437 | 68,254 | 70,659
Electric | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 43,428 | 41,620 | 91,905 | 83,135
Electric | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 9,247 | 11,758 | 18,411 | 23,107
Electric | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 1,793 | 2,065 | 3,643 | 4,001
Natural gas distribution | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (92) | (35) | (187) | (76)
Total external operating revenues | (92) | (35) | (187) | (76)
Natural gas distribution | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 202,186 | 199,288 | 740,306 | 656,852
Other revenues | 4,608 | 2,157 | 5,735 | 4,078
Total external operating revenues | 206,794 | 201,445 | 746,041 | 660,930
Natural gas distribution | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 15,814 | 13,324 | 33,524 | 27,915
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 | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 11,626 | 5,767 | 35,103 | 8,969
Natural gas distribution | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 100,041 | 106,690 | 389,276 | 369,793
Natural gas distribution | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 65,699 | 64,274 | 258,030 | 226,404
Natural gas distribution | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 9,098 | 9,268 | 24,560 | 23,847
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 | (9,796) | (9,035) | (43,132) | (39,325)
Total external operating revenues | (9,796) | (9,035) | (43,132) | (39,325)
Pipeline | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 46,473 | 43,812 | 69,782 | 64,797
Other revenues | 34 | 39 | 49 | 86
Total external operating revenues | 46,507 | 43,851 | 69,831 | 64,883
Pipeline | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 46,120 | 43,406 | 95,373 | 87,043
Pipeline | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 5,172 | 5,331 | 11,202 | 10,713
Pipeline | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 4,977 | 4,110 | 6,339 | 6,366
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
Other | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (180) | (20) | (358) | (42)
Total external operating revenues | (180) | (20) | (358) | (42)
Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | (1) | 2 | 0 | 17
Other revenues | 0 | 0 |  | 0
Total external operating revenues | (1) | 2 | 0 | 17
Other | Natural gas transportation | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 |  | 0
Other | Natural gas storage | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 |  | 0
Other | Other | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 179 | 22 | 358 | 59
Other | Residential utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 |  | 0
Other | Commercial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 |  | 0
Other | Industrial utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | 0 | 0 |  | 0
Other | Other utility sales | Operating Segments |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from contracts with customers | $ 0 | $ 0 |  | $ 0

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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. 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