Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Unrecognized Tax Benefits
Balance at beginning of year	$ 103.5	$ 140.3	$ 237.0
Additions for tax positions of the current year	10.9	7.4	14.5
Additions for tax positions of prior years	1.2	6.6	3.5
Reductions for tax positions of prior years	(6.0)	(15.4)	(8.2)
Settlements	(3.9)	(0.6)	(3.1)
Statute of limitations expiration	(10.6)	(25.5)	(104.6)
Foreign Currency Translation Increases	1.4		1.2
Foreign Currency Translation Decreases		(9.3)
Balance at end of year	$ 96.5	$ 103.5	$ 140.3