Income Taxes (Summary of Income Tax Contingencies) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Unrecognized Tax Benefits [Roll Forward]
Unrecognized tax benefits, beginning of year	$ 7.1	$ 9.2	$ 13.5
Additions based on current year tax positions and acquisitions	0.1	0.0	0.0
Settlements with taxing authorities/statute expirations	(2.0)	(2.1)	(4.3)
Unrecognized tax benefits, end of year	$ 5.2	$ 7.1	$ 9.2