Goodwill (Schedule of Goodwill by Segment) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2012
Goodwill [Line Items]
Goodwill, Beginning Balance	$ 1,598.4
Goodwill, Acquisitions and Adjustments	0.8
Goodwill, Currency Translation and Other	11.5
Goodwill, Ending Balance	1,610.7
Merchant Gases [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	1,138.6
Goodwill, Acquisitions and Adjustments	(1.2)
Goodwill, Currency Translation and Other	7.0
Goodwill, Ending Balance	1,144.4
Tonnage Gases [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	14.7
Goodwill, Acquisitions and Adjustments	0
Goodwill, Currency Translation and Other	0.6
Goodwill, Ending Balance	15.3
Electronics and Performance Materials [Member]
Goodwill [Line Items]
Goodwill, Beginning Balance	445.1
Goodwill, Acquisitions and Adjustments	2.0
Goodwill, Currency Translation and Other	3.9
Goodwill, Ending Balance	$ 451.0