Business Segment and Geographic Information (Schedule of Revenue from External Customers Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Segment Reporting Information [Line Items]
Sales to External Customers	$ 2,605.8	$ 2,340.1	$ 2,344.3	$ 2,321.5	$ 2,506.2	$ 2,472.0	$ 2,403.0	$ 2,292.5	$ 9,611.7	$ 9,673.7	$ 8,616.1
Merchant Gases [Member]
Segment Reporting Information [Line Items]
Sales to External Customers									3,662.4	3,664.9	3,308.4
Tonnage Gases [Member]
Segment Reporting Information [Line Items]
Sales to External Customers									3,206.7	3,316.7	2,930.8
Electronics and Performance Materials [Member]
Segment Reporting Information [Line Items]
Sales to External Customers									2,322.5	2,291.5	1,904.7
Equipment and Energy [Member]
Segment Reporting Information [Line Items]
Sales to External Customers									$ 420.1	$ 400.6	$ 472.2