Acquisitions Other Acquisitions (Details) $ in Millions		3 Months Ended	12 Months Ended
	Jan. 01, 2016 USD ($)	Mar. 31, 2016 USD ($) item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Acquisitions
Number of acquisitions | item		2
Environmental Air Systems
Acquisitions
Interest acquired (as a percent)	40.00%
Total purchase price	$ 46.6
Purchase price paid in cash	$ 42.0
Shoffner
Acquisitions
Interest acquired (as a percent)		100.00%
Total purchase price		$ 19.8
Purchase price paid in cash		15.5
Amount allocated to goodwill and identifiable intangible assets for acquisitions		$ 14.8
Other Acquisitions
Acquisitions
Total purchase price			$ 9.4	$ 0.1