Goodwill (Schedule of Goodwill by Segment) (Details) $ in Millions	3 Months Ended
	Dec. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, net, beginning balance	$ 797.1
Currency translation and other	19.0
Goodwill, net, ending balance	816.1
Industrial Gases - Americas
Goodwill [Roll Forward]
Goodwill, net, beginning balance	156.3
Currency translation and other	(1.7)
Goodwill, net, ending balance	154.6
Industrial Gases - EMEA
Goodwill [Roll Forward]
Goodwill, net, beginning balance	432.3
Currency translation and other	19.2
Goodwill, net, ending balance	451.5
Industrial Gases - Asia
Goodwill [Roll Forward]
Goodwill, net, beginning balance	178.5
Currency translation and other	1.3
Goodwill, net, ending balance	179.8
Industrial Gases - Global
Goodwill [Roll Forward]
Goodwill, net, beginning balance	19.6
Currency translation and other	0.2
Goodwill, net, ending balance	19.8
Corporate and other
Goodwill [Roll Forward]
Goodwill, net, beginning balance	10.4
Currency translation and other	0.0
Goodwill, net, ending balance	$ 10.4