Goodwill (Schedule of Accumulated Impairment Losses) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Goodwill [Line Items]
Goodwill, gross	$ 1,230.2	$ 1,162.2	$ 1,194.7
Goodwill, net	891.5	797.1	788.9
Industrial Gases - Americas
Goodwill [Line Items]
Accumulated impairment losses	(338.7)	(365.1)	(405.8)
Goodwill, net	$ 152.6	$ 156.3	$ 162.1

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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