Income Taxes (Schedule of Unrecognized Tax Benefits Activity) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Unrecognized Tax Benefits [Rollforward]
Unrecognized tax benefits, beginning of year	$ 19.4	$ 21.9	$ 22.4
Additions based on current year tax positions and acquisitions	1.9	2.1	2.0
Settlements with taxing authorities and statute expirations	(1.6)	(4.6)	(2.5)
Unrecognized tax benefits, end of year	$ 19.7	$ 19.4	$ 21.9