Business Segment Information (Schedule of Income Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Segment Reporting Information [Line Items]
Other operating income	$ (1.6)	$ (4.5)	$ (7.7)	$ (10.6)
Operating income	413.8	383.1	1,184.1	1,145.2
Merchant Gases [Member]
Segment Reporting Information [Line Items]
Operating income	173.5	164.9	486.1	504.0
Tonnage Gases [Member]
Segment Reporting Information [Line Items]
Operating income	117.5	119.9	347.3	381.2
Electronics and Performance Materials [Member]
Segment Reporting Information [Line Items]
Operating income	107.0	86.8	297.6	225.6
Equipment and Energy [Member]
Segment Reporting Information [Line Items]
Operating income	17.4	16.0	60.8	45.0
Segment Total [Member]
Segment Reporting Information [Line Items]
Operating income	$ 415.4	$ 387.6	$ 1,191.8	$ 1,155.8