Business Segment Information (Schedule of Assets Information) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Sep. 30, 2012
Segment Reporting Information [Line Items]
Identifiable Assets	$ 16,702.5	[1]	$ 16,654.6	[1]
Merchant Gases [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	6,735.1	[1]	6,729.9	[1]
Tonnage Gases [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	5,460.3	[1]	5,397.0	[1]
Electronics and Performance Materials [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	2,868.9	[1]	2,859.4	[1]
Equipment and Energy [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	762.0	[1]	675.2	[1]
Segment Total [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	15,826.3	[1]	15,661.5	[1]
All Other Segments [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	876.2	[1]	990.6	[1]
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	$ 0	[1]	$ 2.5	[1]

[1] Identifiable assets are equal to total assets less investment in net assets of and advances to equity affiliates.