Accrued Warranty Costs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Changes in product warranty liability [Roll Forward]
Balance at beginning of period	$ 7.9	$ 7.1
Claims paid	(3.1)	(3.0)
Warranty expense	2.5	3.6
Balance at end of period	$ 7.3	$ 7.7