Guarantees (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of period	$ 25.3	$ 26.3	$ 25.5	$ 27.5
Provision for warranties during the period	4.0	3.7	7.5	6.3
Standard Product Warranty Accrual, Additions from Business Acquisition	0.0	1.9	0.0	1.9
Warranty claims during the period	(4.3)	(4.5)	(8.0)	(8.3)
Balance at end of period	$ 25.0	$ 27.4	$ 25.0	$ 27.4