Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) segment	Sep. 30, 2020 USD ($)
Segment Information
Number of reportable segments | segment			2
Revenue	$ 833,896	$ 714,099	$ 2,217,552	$ 2,157,698
Gross Profit	159,212	147,196	409,136	409,984
Operating | Mechanical Services Segment
Segment Information
Revenue	690,680	625,660	1,868,096	1,823,117
Gross Profit	138,618	139,845	359,151	386,537
Operating | Electrical Services Industry
Segment Information
Revenue	143,216	88,439	349,456	334,581
Gross Profit	$ 20,594	$ 7,351	$ 49,985	$ 23,447