Business Segment and Geographic Information (Schedule of Revenue from External Customers Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Segment Reporting Information [Line Items]
Sales to External Customers	$ 2,340.1	$ 2,472.0	$ 7,005.9	$ 7,167.5
Merchant Gases [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	874.1	921.4	2,645.4	2,724.5
Tonnage Gases [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	767.4	868.7	2,360.7	2,433.9
Electronics and Performance Materials [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	603.8	602.4	1,706.0	1,704.3
Equipment and Energy [Member]
Segment Reporting Information [Line Items]
Sales to External Customers	$ 94.8	$ 79.5	$ 293.8	$ 304.8