Goodwill (Schedule of Goodwill by Segment) (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
		Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance			$ 1,237.3	$ 1,653.8
Goodwill, Acquisitions and Adjustments			5.4
Goodwill, Impairment Loss		$ (305.2)		(305.2)
Goodwill, Currency Translation and Other			(111.4)	(111.3)
Goodwill, net, Ending Balance		1,237.3	1,131.3	1,237.3
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, gross					$ 1,375.0	$ 1,522.1	$ 1,653.8
Goodwill, Accumulated impairment losses	[1]				(243.7)	(284.8)	0.0
Goodwill, net		1,237.3	1,131.3	1,237.3	1,131.3	1,237.3	1,653.8
Industrial Gases - Americas [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance			327.2	714.2
Goodwill, Acquisitions and Adjustments			2.2
Goodwill, Impairment Loss				(305.2)
Goodwill, Currency Translation and Other			(31.8)	(81.8)
Goodwill, net, Ending Balance		327.2	297.6	327.2
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		327.2	327.2	714.2	297.6	327.2	714.2
Goodwill, Accumulated impairment losses currency translation			61.5	20.4
Industrial Gases - EMEA [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance			433.3	459.0
Goodwill, Acquisitions and Adjustments			3.2
Goodwill, Impairment Loss				0.0
Goodwill, Currency Translation and Other			(50.0)	(25.7)
Goodwill, net, Ending Balance		433.3	386.5	433.3
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		433.3	433.3	459.0	386.5	433.3	459.0
Industrial Gases - Asia [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance			140.0	140.5
Goodwill, Acquisitions and Adjustments			0.0
Goodwill, Impairment Loss				0.0
Goodwill, Currency Translation and Other			(6.9)	(0.5)
Goodwill, net, Ending Balance		140.0	133.1	140.0
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		140.0	140.0	140.5	133.1	140.0	140.5
Industrial Gases - Global [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance			21.4	20.9
Goodwill, Acquisitions and Adjustments			0.0
Goodwill, Impairment Loss				0.0
Goodwill, Currency Translation and Other			(1.5)	0.5
Goodwill, net, Ending Balance		21.4	19.9	21.4
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		21.4	21.4	20.9	19.9	21.4	20.9
Materials Technologies [Member]
Goodwill [Roll Forward]
Goodwill, net, Beginning Balance			315.4	319.2
Goodwill, Acquisitions and Adjustments			0.0
Goodwill, Impairment Loss				0.0
Goodwill, Currency Translation and Other			(21.2)	(3.8)
Goodwill, net, Ending Balance		315.4	294.2	315.4
Goodwill Impaired Accumulated Impairment Loss Abstract
Goodwill, net		$ 315.4	$ 315.4	$ 319.2	$ 294.2	$ 315.4	$ 319.2

[1] Amount is attributable to the Industrial Gases – Americas segment and includes currency translation of $61.5 and $20.4 as of 30 September 2015 and 30 September 2014, respectively.