Goodwill (Schedule of Accumulated Impairment Losses) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Sep. 30, 2025
Intangible Asset, Goodwill and Other [Abstract]
Goodwill, gross	$ 1,244.4	$ 1,238.6
Accumulated impairment losses	(287.0)	(274.7)
Goodwill, net	$ 957.4	$ 963.9

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

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