Revenue Recognition - Schedule of revenue by contract type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Contract revenues	$ 939,476	$ 799,848	$ 2,639,708	$ 2,144,586
Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	100.00%	100.00%	100.00%	100.00%
Fixed price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 602,986	$ 506,160	$ 1,712,598	$ 1,312,257
Fixed price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	64.20%	63.30%	64.90%	61.20%
Unit price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 170,117	$ 154,718	$ 464,954	$ 409,383
Unit price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	18.10%	19.30%	17.60%	19.10%
T&E
Disaggregation of Revenue [Line Items]
Contract revenues	$ 166,373	$ 138,970	$ 462,156	$ 422,946
T&E | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	17.70%	17.40%	17.50%	19.70%
T&D
Disaggregation of Revenue [Line Items]
Contract revenues	$ 548,595	$ 452,014	$ 1,497,655	$ 1,232,105
T&D | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	100.00%	100.00%	100.00%	100.00%
T&D | Fixed price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 283,440	$ 216,082	$ 774,022	$ 559,920
T&D | Fixed price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	51.70%	47.80%	51.70%	45.50%
T&D | Unit price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 143,218	$ 127,121	$ 396,855	$ 349,051
T&D | Unit price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	26.10%	28.10%	26.50%	28.30%
T&D | T&E
Disaggregation of Revenue [Line Items]
Contract revenues	$ 121,937	$ 108,811	$ 326,778	$ 323,134
T&D | T&E | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	22.20%	24.10%	21.80%	26.20%
C&I
Disaggregation of Revenue [Line Items]
Contract revenues	$ 390,881	$ 347,834	$ 1,142,053	$ 912,481
C&I | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	100.00%	100.00%	100.00%	100.00%
C&I | Fixed price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 319,546	$ 290,078	$ 938,576	$ 752,337
C&I | Fixed price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	81.70%	83.40%	82.20%	82.50%
C&I | Unit price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 26,899	$ 27,597	$ 68,099	$ 60,332
C&I | Unit price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	6.90%	7.90%	6.00%	6.60%
C&I | T&E
Disaggregation of Revenue [Line Items]
Contract revenues	$ 44,436	$ 30,159	$ 135,378	$ 99,812
C&I | T&E | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	11.40%	8.70%	11.80%	10.90%