Revenue from Contracts with Customers - Schedule of Disaggregation of Revenues (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 2,592,549	$ 2,304,049
UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		2,461,052	2,177,314
United States Electrical Construction And Facilities Services [Member] | UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		522,030	459,395
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		523,010	460,605
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Commercial Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 270,315	$ 245,841
Percent of individual segment		52.00%	53.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Manufacturing Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 66,465	$ 48,454
Percent of individual segment		13.00%	11.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Healthcare Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 32,070	$ 20,151
Percent of individual segment		6.00%	4.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Institutional Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 31,766	$ 43,639
Percent of individual segment		6.00%	9.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Transportation Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 45,082	$ 42,031
Percent of individual segment		8.00%	9.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Water and Wastewater Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 5,312	$ 3,651
Percent of individual segment		1.00%	1.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Hospitality Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 2,623	$ 4,664
Percent of individual segment		1.00%	1.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Short Duration Projects [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities	[1]	$ 56,048	$ 44,409
Percent of individual segment		11.00%	10.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Service Work [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 13,329	$ 7,765
Percent of individual segment		2.00%	2.00%
United States Electrical Construction And Facilities Services [Member] | UNITED STATES | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ (980)	$ (1,210)
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		1,000,470	914,501
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		1,002,738	916,172
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Commercial Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 379,604	$ 366,477
Percent of individual segment		38.00%	40.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Manufacturing Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 149,571	$ 121,686
Percent of individual segment		15.00%	13.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Healthcare Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 120,051	$ 112,656
Percent of individual segment		12.00%	12.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Institutional Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 70,627	$ 69,304
Percent of individual segment		7.00%	8.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Transportation Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 16,053	$ 18,417
Percent of individual segment		2.00%	2.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Water and Wastewater Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 61,744	$ 43,848
Percent of individual segment		6.00%	5.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Hospitality Market Sector [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 8,079	$ 8,529
Percent of individual segment		1.00%	1.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Short Duration Projects [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities	[1]	$ 62,294	$ 86,765
Percent of individual segment		6.00%	9.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Operating Segments [Member] | Service Work [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 134,715	$ 88,490
Percent of individual segment		13.00%	10.00%
United States Mechanical Construction And Facilities Services [Member] | UNITED STATES | Intersegment Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ (2,268)	$ (1,671)
United States Building Services [Member] | UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		627,801	568,036
United States Building Services [Member] | UNITED STATES | Mobile Mechanical Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 373,571	$ 351,317
Percent of individual segment		60.00%	62.00%
United States Building Services [Member] | UNITED STATES | Commercial Site-Based Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 203,550	$ 175,647
Percent of individual segment		32.00%	31.00%
United States Building Services [Member] | UNITED STATES | Government Site-Based Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 50,680	$ 41,072
Percent of individual segment		8.00%	7.00%
United States Industrial Services [Member] | UNITED STATES
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 310,751	$ 235,382
United States Industrial Services [Member] | UNITED STATES | Field Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 271,418	$ 207,554
Percent of individual segment		87.00%	88.00%
United States Industrial Services [Member] | UNITED STATES | Shop Services [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 39,333	$ 27,828
Percent of individual segment		13.00%	12.00%
United Kingdom Building Services [Member] [Member] | UNITED KINGDOM
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 131,497	$ 126,735
United Kingdom Building Services [Member] [Member] | UNITED KINGDOM | Service Work [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 64,817	$ 61,991
Percent of individual segment		49.00%	49.00%
United Kingdom Building Services [Member] [Member] | UNITED KINGDOM | Project Work [Member]
Disaggregation of Revenue [Line Items]
Revenues from unrelated entities		$ 66,680	$ 64,744
Percent of individual segment		51.00%	51.00%

[1] Represents those projects which generally are completed within three months or less.