Acquisitions (Details) $ in Millions		3 Months Ended			9 Months Ended
	Jan. 01, 2016 USD ($)	Mar. 31, 2016 USD ($) item	Sep. 30, 2015 item	Mar. 31, 2015 item	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)
Acquisitions
Number of acquisitions | item		2
Environmental Air Systems
Acquisitions
Total purchase price	$ 47.0
Interest acquired (as a percent)	40.00%
Purchase price paid in cash	$ 42.0
Shoffner
Acquisitions
Total purchase price					$ 20.1
Interest acquired (as a percent)		100.00%
Amount allocated to goodwill and identifiable intangible assets for acquisitions					14.4
Revenue in consolidated results					55.3
Purchase price paid in cash					$ 15.5
Other Acquisitions
Acquisitions
Total purchase price						$ 7.1
Number of acquisitions | item			1	2
Purchase price paid in cash		$ 0.8