Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at October 1	$ 5.1	$ 5.8	$ 4.1
Increases in tax position of prior years	0.1	0.8	0.4
Decreases in tax position of prior years	0.0	(0.1)	(1.3)
Settlements with taxing authorities	0.0	(0.3)	(1.2)
Lapse of applicable statute of limitations	(0.8)	(0.5)	(1.3)
Change in positions due to acquisitions	0.0	(0.6)	5.5
Foreign currency adjustments	0.1	0.0	(0.4)
Total change	(0.6)	(0.7)	1.7
Balance at September 30	$ 4.5	$ 5.1	$ 5.8