Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Unrecognized Tax Benefits
Balance at beginning of year	$ 101.0	$ 96.5	$ 103.5
Additions for tax positions of the current year	21.2	14.6	10.9
Additions for tax positions of prior years	92.6	1.4	1.2
Reductions for tax positions of prior years	(0.6)	(0.3)	(6.0)
Settlements	0.0	(3.7)	(3.9)
Statute of limitations expiration	(20.0)	(9.9)	(10.6)
Foreign currency translation	0.6	2.4	1.4
Balance at end of year	$ 194.8	$ 101.0	$ 96.5