Goodwill (Schedule of Goodwill by Segment) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Goodwill [Roll Forward]
Goodwill, net, beginning balance		$ 845.1
Impairment loss	$ (145.3)	(145.3)
Currency translation		5.3
Goodwill, net, ending balance	705.1	705.1
Industrial Gases - Americas [Member]
Goodwill [Roll Forward]
Goodwill, net, beginning balance		309.1
Impairment loss		(145.3)
Currency translation		(2.3)
Goodwill, net, ending balance	161.5	161.5
Industrial Gases - EMEA [Member]
Goodwill [Roll Forward]
Goodwill, net, beginning balance		380.6
Impairment loss		0.0
Currency translation		8.1
Goodwill, net, ending balance	388.7	388.7
Industrial Gases - Asia [Member]
Goodwill [Roll Forward]
Goodwill, net, beginning balance		135.2
Impairment loss		0.0
Currency translation		(0.3)
Goodwill, net, ending balance	134.9	134.9
Industrial Gases - Global [Member]
Goodwill [Roll Forward]
Goodwill, net, beginning balance		20.2
Impairment loss		0.0
Currency translation		(0.2)
Goodwill, net, ending balance	$ 20.0	$ 20.0