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Disaggregation of revenue (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | $ 1,362,928 | $ 1,303,573 | $ 2,560,302 | $ 2,394,764
Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (12,222) | (11,281) | (43,306) | (43,285)
Intrasegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (164,719) | (145,925) | (208,823) | (181,066)
Natural gas transportation |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 38,315 | 35,510 | 77,545 | 72,138
Natural gas gathering |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,181 | 2,396 | 3,271 | 4,517
Natural gas storage |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 3,104 | 2,623 | 6,150 | 5,269
Contracting services |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 303,356 | 297,124 | 401,757 | 380,164
Construction materials |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 482,498 | 444,768 | 690,408 | 624,077
Inside specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 324,921 | 319,276 | 697,130 | 618,805
Outside specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 160,696 | 133,288 | 290,846 | 240,686
Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 17,064 | 20,545 | 34,595 | 44,136
Revenues from contracts with customers |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,347,026 | 1,287,052 | 2,530,574 | 2,368,092
Revenues out of scope |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 15,902 | 16,521 | 29,728 | 26,672
Residential utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 106,607 | 97,447 | 325,657 | 334,612
Commercial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 70,904 | 74,481 | 219,487 | 231,945
Industrial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 13,730 | 14,921 | 32,618 | 32,416
Other utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,591 | 1,879 | 3,239 | 3,678
Electric |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 76,438 | 81,011 | 162,346 | 173,578
Electric | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (196) | 0 | (391) | 0
Electric | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 7,717 | 8,417 | 16,167 | 17,538
Electric | Revenues from contracts with customers |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 75,015 | 79,308 | 161,221 | 171,339
Electric | Revenues out of scope |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,423 | 1,703 | 1,125 | 2,239
Electric | Residential utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 27,954 | 26,437 | 60,303 | 62,993
Electric | Commercial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 29,877 | 33,231 | 63,464 | 68,902
Electric | Industrial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 8,072 | 9,344 | 18,439 | 18,228
Electric | Other utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,591 | 1,879 | 3,239 | 3,678
Natural gas distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 141,494 | 133,867 | 467,937 | 476,014
Natural gas distribution | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (185) | 0 | (370) | 0
Natural gas distribution | Natural gas transportation |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 10,350 | 10,706 | 22,148 | 22,276
Natural gas distribution | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 2,711 | 2,923 | 5,209 | 6,836
Natural gas distribution | Revenues from contracts with customers |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 138,214 | 131,466 | 462,543 | 477,962
Natural gas distribution | Revenues out of scope |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 3,280 | 2,401 | 5,394 | (1,948)
Natural gas distribution | Residential utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 78,653 | 71,010 | 265,354 | 271,619
Natural gas distribution | Commercial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 41,027 | 41,250 | 156,023 | 163,043
Natural gas distribution | Industrial utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 5,658 | 5,577 | 14,179 | 14,188
Natural gas distribution | Other utility sales |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Pipeline |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 27,658 | 28,680 | 38,313 | 37,293
Pipeline | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (7,999) | (7,513) | (33,198) | (31,468)
Pipeline | Natural gas transportation |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 27,965 | 24,804 | 55,397 | 49,862
Pipeline | Natural gas gathering |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,181 | 2,396 | 3,271 | 4,517
Pipeline | Natural gas storage |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 3,104 | 2,623 | 6,150 | 5,269
Pipeline | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 3,363 | 6,293 | 6,604 | 8,989
Pipeline | Revenues from contracts with customers |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 27,614 | 28,603 | 38,224 | 37,169
Pipeline | Revenues out of scope |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 44 | 77 | 89 | 124
Construction materials and contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 621,045 | 595,799 | 883,190 | 822,911
Construction materials and contracting | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (90) | (168) | (152) | (264)
Construction materials and contracting | Intrasegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (164,719) | (145,925) | (208,823) | (181,066)
Construction materials and contracting | Contracting services |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 303,356 | 297,124 | 401,757 | 380,164
Construction materials and contracting | Construction materials |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 482,498 | 444,768 | 690,408 | 624,077
Construction materials and contracting | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Construction materials and contracting | Revenues from contracts with customers |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 621,045 | 595,799 | 883,190 | 822,911
Construction materials and contracting | Revenues out of scope |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Construction services |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 496,405 | 464,192 | 1,008,610 | 884,925
Construction services | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (779) | (721) | (3,249) | (849)
Construction services | Inside specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 324,921 | 319,276 | 697,130 | 618,805
Construction services | Outside specialty contracting |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 160,696 | 133,288 | 290,846 | 240,686
Construction services | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 412 | 9 | 763 | 26
Construction services | Revenues from contracts with customers |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 485,250 | 451,852 | 985,490 | 858,668
Construction services | Revenues out of scope |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 11,155 | 12,340 | 23,120 | 26,257
Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (112) | 24 | (94) | 43
Other | Intersegment eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (2,973) | (2,879) | (5,946) | (10,704)
Other | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 2,861 | 2,903 | 5,852 | 10,747
Other | Revenues from contracts with customers |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (112) | 24 | (94) | 43
Other | Revenues out of scope |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | $ 0 | $ 0 | $ 0 | $ 0

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