Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue
Revenue	$ 3,073,636	$ 2,856,659	$ 2,615,277
Percentage of revenue from contract with customer (as a percent)	100.00%	100.00%	100.00%
Industrial
Disaggregation of Revenue
Revenue	$ 1,356,688	$ 1,112,075	$ 886,668
Percentage of revenue from contract with customer (as a percent)	44.10%	38.90%	33.90%
Education
Disaggregation of Revenue
Revenue	$ 390,251	$ 487,922	$ 412,318
Percentage of revenue from contract with customer (as a percent)	12.70%	17.10%	15.80%
Office Buildings
Disaggregation of Revenue
Revenue	$ 308,799	$ 319,426	$ 348,640
Percentage of revenue from contract with customer (as a percent)	10.10%	11.20%	13.30%
Healthcare
Disaggregation of Revenue
Revenue	$ 417,901	$ 371,105	$ 358,155
Percentage of revenue from contract with customer (as a percent)	13.60%	13.00%	13.70%
Government
Disaggregation of Revenue
Revenue	$ 174,813	$ 163,717	$ 162,507
Percentage of revenue from contract with customer (as a percent)	5.70%	5.70%	6.20%
Retail, Restaurants and Entertainment
Disaggregation of Revenue
Revenue	$ 213,386	$ 239,541	$ 248,083
Percentage of revenue from contract with customer (as a percent)	6.90%	8.40%	9.50%
Multi-Family and Residential
Disaggregation of Revenue
Revenue	$ 112,779	$ 86,799	$ 104,693
Percentage of revenue from contract with customer (as a percent)	3.70%	3.00%	4.00%
Other
Disaggregation of Revenue
Revenue	$ 99,019	$ 76,074	$ 94,213
Percentage of revenue from contract with customer (as a percent)	3.20%	2.70%	3.60%
New Construction
Disaggregation of Revenue
Revenue	$ 1,421,784	$ 1,333,739	$ 1,201,122
Percentage of revenue from contract with customer (as a percent)	46.30%	46.70%	45.90%
Existing Building Construction
Disaggregation of Revenue
Revenue	$ 963,461	$ 910,807	$ 793,159
Percentage of revenue from contract with customer (as a percent)	31.30%	31.90%	30.30%
Service Projects
Disaggregation of Revenue
Revenue	$ 278,582	$ 241,402	$ 231,228
Percentage of revenue from contract with customer (as a percent)	9.10%	8.40%	8.90%
Service Calls, Maintenance and Monitoring
Disaggregation of Revenue
Revenue	$ 409,809	$ 370,711	$ 389,768
Percentage of revenue from contract with customer (as a percent)	13.30%	13.00%	14.90%
Mechanical Services
Disaggregation of Revenue
Revenue	$ 2,542,623	$ 2,430,632	$ 2,272,031
Percentage of revenue from contract with customer (as a percent)	82.70%	85.10%	86.90%
Electrical Services
Disaggregation of Revenue
Revenue	$ 531,013	$ 426,027	$ 343,246
Percentage of revenue from contract with customer (as a percent)	17.30%	14.90%	13.10%