Goodwill (Schedule of Goodwill by Segment) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Jun. 30, 2014
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 1,653.8
Goodwill, Currency Translation and Other	(41.3)
Goodwill, Ending Balance	1,612.5
Merchant Gases [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	1,192.0
Goodwill, Currency Translation and Other	(48.7)
Goodwill, Ending Balance	1,143.3
Tonnage Gases [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	15.2
Goodwill, Currency Translation and Other	0.7
Goodwill, Ending Balance	15.9
Electronics and Performance Materials [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	446.6
Goodwill, Currency Translation and Other	6.7
Goodwill, Ending Balance	$ 453.3