Goodwill (Schedule of Accumulated Impairment Losses) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Goodwill [Line Items]
Goodwill, gross	$ 1,158.4	$ 1,096.0	$ 1,239.2
Goodwill, net	861.7	823.0	911.5
Americas
Goodwill [Line Items]
Accumulated impairment losses	(296.7)	(273.0)	(327.7)
Goodwill, net	$ 146.6	$ 143.2	$ 151.0