Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of October 1	$ 9.6	$ 6.2	$ 4.5
Increases in tax position of prior years	0.0	5.8	2.3
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	0.0	0.0	0.3
Settlements with taxing authorities	(5.8)	(1.1)	0.0
Lapse of applicable statute of limitations	(0.2)	(1.0)	(0.9)
Foreign currency adjustments	0.3	(0.3)	0.0
Total change	(5.7)	3.4	1.7
Balance as of September 30	3.9	9.6	6.2
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Unrecognized tax benefits that would impact effective tax rate, if recognized	$ 3.5	$ 9.3	$ 5.6