Business Segment And Geographic Information (Segment Identifiable Assets Information) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012		Sep. 30, 2011
Segment Reporting Information [Line Items]
Identifiable Assets	$ 12,476.0	[1]	$ 11,868.4	[1]
Other	836.0		878.6
Discontinued operations	592.3		532.1
Consolidated Identifiable Assets Total	13,904.3	[1]	13,279.1	[1]
Merchant Gases [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	4,759.3	[1]	4,579.6	[1]
Tonnage Gases [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	4,793.4	[1]	4,464.3	[1]
Electronics And Performance Materials [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	2,634.9	[1]	2,488.9	[1]
Equipment And Energy [Member]
Segment Reporting Information [Line Items]
Identifiable Assets	$ 288.4	[1]	$ 335.6	[1]

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