Business Segment and Geographic Information (Schedule of Revenue from External Customers Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Segment Reporting Information [Line Items]
Sales to External Customers	$ 2,484.2	$ 2,344.3	$ 5,046.6	$ 4,665.8
Merchant Gases [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	1,003.2	883.6	2,012.3	1,771.3
Tonnage Gases [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	808.5	783.5	1,706.9	1,593.3
Electronics and Performance Materials [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	548.8	567.0	1,097.8	1,102.2
Equipment and Energy [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	$ 123.7	$ 110.2	$ 229.6	$ 199.0