Goodwill (Schedule of Goodwill by Segment) (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
		Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2015
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		$ 1,237.3
Goodwill, Acquisitions and Adjustments		5.4
Goodwill, Currency Translation and Other		(78.9)
Goodwill, net, Ending Balance		1,163.8	$ 1,237.3
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, gross			1,522.1	$ 1,430.0
Goodwill, Accumulated impairment losses	[1]		(284.8)	(266.2)
Goodwill, net		1,237.3	1,237.3	1,163.8
Industrial Gases - Americas [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		327.2
Goodwill, Acquisitions and Adjustments		2.2
Goodwill, Currency Translation and Other		(14.5)
Goodwill, net, Ending Balance		314.9	327.2
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, Accumulated impairment losses	[1]		(284.8)	(266.2)
Goodwill, net		314.9	327.2	314.9
Goodwill, Accumulated impairment losses currency translation		39.0	20.4
Industrial Gases - EMEA [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		433.3
Goodwill, Acquisitions and Adjustments		3.2
Goodwill, Currency Translation and Other		(47.3)
Goodwill, net, Ending Balance		389.2	433.3
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		433.3	433.3	389.2
Industrial Gases - Asia [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		140.0
Goodwill, Acquisitions and Adjustments		0.0
Goodwill, Currency Translation and Other		(3.7)
Goodwill, net, Ending Balance		136.3	140.0
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		136.3	140.0	136.3
Industrial Gases - Global [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		21.4
Goodwill, Acquisitions and Adjustments		0.0
Goodwill, Currency Translation and Other		(1.1)
Goodwill, net, Ending Balance		20.3	21.4
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		21.4	21.4	20.3
Materials Technologies [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance		315.4
Goodwill, Acquisitions and Adjustments		0.0
Goodwill, Currency Translation and Other		(12.3)
Goodwill, net, Ending Balance		303.1	315.4
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		$ 303.1	$ 315.4	$ 303.1

[1] Amount is attributable to the Industrial Gases – Americas segment and includes currency translation of $39.0 and $20.4 as of 30 June 2015 and 30 September 2014, respectively.