Goodwill (Schedule of Goodwill by Segment) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2016	Sep. 30, 2015
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		$ 1,131.3	$ 1,237.3
Goodwill, Acquisitions and Adjustments		0.0	5.4
Goodwill, Impairment Loss	$ (305.2)
Goodwill, Currency Translation and Other		18.9	(111.4)
Goodwill, net, Ending Balance	1,237.3	1,150.2	1,131.3
Industrial Gases - Americas [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		297.6	327.2
Goodwill, Acquisitions and Adjustments		0.0	2.2
Goodwill, Currency Translation and Other		11.5	(31.8)
Goodwill, net, Ending Balance	327.2	309.1	297.6
Industrial Gases - EMEA [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		386.5	433.3
Goodwill, Acquisitions and Adjustments		0.0	3.2
Goodwill, Currency Translation and Other		(5.9)	(50.0)
Goodwill, net, Ending Balance	433.3	380.6	386.5
Industrial Gases - Asia [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		133.1	140.0
Goodwill, Acquisitions and Adjustments		0.0	0.0
Goodwill, Currency Translation and Other		2.1	(6.9)
Goodwill, net, Ending Balance	140.0	135.2	133.1
Industrial Gases - Global [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		19.9	21.4
Goodwill, Acquisitions and Adjustments		0.0	0.0
Goodwill, Currency Translation and Other		0.3	(1.5)
Goodwill, net, Ending Balance	21.4	20.2	19.9
Materials Technologies [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		294.2	315.4
Goodwill, Acquisitions and Adjustments		0.0	0.0
Goodwill, Currency Translation and Other		10.9	(21.2)
Goodwill, net, Ending Balance	$ 315.4	$ 305.1	$ 294.2