Business Segment Information (Schedule of Income Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information [Line Items]
Other operating income	$ (0.9)	$ 0.3	$ (6.1)	$ (6.1)
Operating income	384.7	389.7	770.3	762.1
Merchant Gases [Member]
Segment Reporting Information [Line Items]
Operating income	143.4	168.1	312.6	339.1
Tonnage Gases [Member]
Segment Reporting Information [Line Items]
Operating income	112.2	123.2	229.8	261.3
Electronics and Performance Materials [Member]
Segment Reporting Information [Line Items]
Operating income	107.1	77.5	190.6	138.8
Equipment and Energy [Member]
Segment Reporting Information [Line Items]
Operating income	22.9	20.6	43.4	29.0
Segment Total [Member]
Segment Reporting Information [Line Items]
Operating income	$ 385.6	$ 389.4	$ 776.4	$ 768.2