Goodwill (Schedule of Goodwill by Segment) (Details) $ in Millions	9 Months Ended
Jun. 30, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, net, beginning balance	$ 788.9
Acquisitions	42.2
Currency translation and other	(10.7)
Goodwill, net, ending balance	820.4
Industrial Gases - Americas
Goodwill [Roll Forward]
Goodwill, net, beginning balance	162.1
Acquisitions	0.0
Currency translation and other	(1.9)
Goodwill, net, ending balance	160.2
Industrial Gases - EMEA
Goodwill [Roll Forward]
Goodwill, net, beginning balance	424.4
Acquisitions	38.0
Currency translation and other	(7.5)
Goodwill, net, ending balance	454.9
Industrial Gases - Asia
Goodwill [Roll Forward]
Goodwill, net, beginning balance	171.9
Acquisitions	4.2
Currency translation and other	(1.1)
Goodwill, net, ending balance	175.0
Industrial Gases - Global
Goodwill [Roll Forward]
Goodwill, net, beginning balance	20.1
Acquisitions	0.0
Currency translation and other	(0.2)
Goodwill, net, ending balance	19.9
Corporate and other
Goodwill [Roll Forward]
Goodwill, net, beginning balance	10.4
Acquisitions	0.0
Currency translation and other	0.0
Goodwill, net, ending balance	$ 10.4

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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