Business and Organization (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business and Organization
Revenue	$ 465,411	$ 427,538	$ 845,999	$ 813,480
Percentage of revenue attributable to services			100.00%
Installation of systems in newly constructed facilities
Business and Organization
Percentage of revenue attributable to services			39.00%
Maintenance, repair and replacement services
Business and Organization
Percentage of revenue attributable to services			61.00%
Heating Ventilation Air Conditioning And Plumbing [Member]
Business and Organization
Revenue			$ 761,399
Percentage of revenue attributable to services			90.00%
Building Automation Control Systems
Business and Organization
Revenue			$ 50,760
Percentage of revenue attributable to services			6.00%
Other
Business and Organization
Revenue			$ 33,840
Percentage of revenue attributable to services			4.00%