Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Unrecognized Tax Benefits
Balance at beginning of year	$ 237.0	$ 231.7	$ 233.6
Additions for tax positions of the current year	14.5	7.6	7.8
Additions for tax positions of prior years	3.5	17.7	14.2
Reductions for tax positions of prior years	(8.2)	(4.1)	(14.7)
Settlements	(3.1)	(1.2)	(1.5)
Statute of limitations expiration	(104.6)	(14.0)	(3.9)
Foreign currency translation	1.2
Foreign currency translation		(0.7)	(3.8)
Balance at end of year	$ 140.3	$ 237.0	$ 231.7