Basis of Presentation and Major Accounting Policies (Allowance for Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Allowance for Credit Losses
Beginning balance	$ 24.1	$ 25.1	$ 23.9
Adoption of new credit losses standard			0.5
Provision for credit losses	8.2	7.5	2.7
Write-offs charged against the allowance	(7.9)	(7.9)	(3.8)
Currency translation and other	(1.5)	(0.6)	1.8
Ending balance	$ 22.9	$ 24.1	$ 25.1