Goodwill (Schedule of Accumulated Impairment Losses) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Sep. 30, 2020
Goodwill [Line Items]
Goodwill, gross	$ 1,298.5	$ 1,230.2
Goodwill, net	923.9	891.5
Industrial Gases - Americas
Goodwill [Line Items]
Goodwill, accumulated impairment losses	(374.6)	(338.7)
Goodwill, net	$ 157.7	$ 152.6

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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