Revenue Recognition - Schedule of revenue by contract type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Contract revenues	$ 799,848	$ 610,182	$ 2,144,586	$ 1,852,241
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	$ 506,160	$ 368,988	$ 1,312,257	$ 1,165,359
Fixed price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	63.30%	60.50%	61.20%	62.90%
Unit price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 154,718	$ 104,767	$ 409,383	$ 316,966
Unit price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	19.30%	17.20%	19.10%	17.10%
T&E
Disaggregation of Revenue [Line Items]
Contract revenues	$ 138,970	$ 136,427	$ 422,946	$ 369,916
T&E | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	17.40%	22.30%	19.70%	20.00%
T&D
Disaggregation of Revenue [Line Items]
Contract revenues	$ 452,014	$ 306,546	$ 1,232,105	$ 948,285
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	$ 216,082	$ 122,185	$ 559,920	$ 431,673
T&D | Fixed price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	47.80%	39.90%	45.50%	45.50%
T&D | Unit price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 127,121	$ 83,200	$ 349,051	$ 258,489
T&D | Unit price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	28.10%	27.10%	28.30%	27.30%
T&D | T&E
Disaggregation of Revenue [Line Items]
Contract revenues	$ 108,811	$ 101,161	$ 323,134	$ 258,123
T&D | T&E | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	24.10%	33.00%	26.20%	27.20%
C&I
Disaggregation of Revenue [Line Items]
Contract revenues	$ 347,834	$ 303,636	$ 912,481	$ 903,956
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	$ 290,078	$ 246,803	$ 752,337	$ 733,686
C&I | Fixed price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	83.40%	81.30%	82.50%	81.20%
C&I | Unit price
Disaggregation of Revenue [Line Items]
Contract revenues	$ 27,597	$ 21,567	$ 60,332	$ 58,477
C&I | Unit price | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	7.90%	7.10%	6.60%	6.50%
C&I | T&E
Disaggregation of Revenue [Line Items]
Contract revenues	$ 30,159	$ 35,266	$ 99,812	$ 111,793
C&I | T&E | Product concentration risk | Revenue benchmark
Disaggregation of Revenue [Line Items]
Concentration risk, Percent	8.70%	11.60%	10.90%	12.30%