Goodwill (Schedule of Goodwill by Segment) (Details) $ in Millions	3 Months Ended
	Dec. 31, 2020 USD ($)
Goodwill [Roll Forward]
Goodwill, net, beginning balance	$ 891.5
Currency translation and other	32.4
Goodwill, net, ending balance	923.9
Industrial Gases - Americas
Goodwill [Roll Forward]
Goodwill, net, beginning balance	152.6
Currency translation and other	5.1
Goodwill, net, ending balance	157.7
Industrial Gases - EMEA
Goodwill [Roll Forward]
Goodwill, net, beginning balance	524.1
Currency translation and other	22.8
Goodwill, net, ending balance	546.9
Industrial Gases - Asia
Goodwill [Roll Forward]
Goodwill, net, beginning balance	180.4
Currency translation and other	4.1
Goodwill, net, ending balance	184.5
Industrial Gases - Global
Goodwill [Roll Forward]
Goodwill, net, beginning balance	19.5
Currency translation and other	0.4
Goodwill, net, ending balance	19.9
Corporate and other
Goodwill [Roll Forward]
Goodwill, net, beginning balance	14.9
Currency translation and other	0.0
Goodwill, net, ending balance	$ 14.9