Consolidated Comprehensive Income Statement (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Other Comprehensive Income (Loss), net of tax [Abstract]
Net Income	$ 1,193.3	$ 1,261.5	$ 1,054.5
Translation adjustments, net of tax	84.6	(82.8)	138.4
Net gain (loss) on derivatives, net of tax	(21.8)	0.8	(11.6)
Unrealized holding gain (loss) on available-for-sale securities, net of tax	0	(4.6)	20.2
Pension and postretirement benefits, net of tax	(246.0)	(66.6)	(201.9)
Reclassification Adjustments [Abstract]
Currency translation adjustment	13.3	0.4	(0.7)
Derivatives, net of tax	12.4	11.5	14.8
Available-for-sale securities, net of tax	0	(16.1)	(10.0)
Pension and postretirement benefits, net of tax	67.0	67.7	55.0
Total Other Comprehensive Income (Loss)	(90.5)	(89.7)	4.2
Comprehensive Income	1,102.8	1,171.8	1,058.7
Net income attributable to noncontrolling interests	26.0	37.3	25.4
Other Comprehensive Income Attributable to Noncontrolling Interests	4.9	4.3	1.8
Comprehensive Income Attributable to Air Products	$ 1,071.9	$ 1,130.2	$ 1,031.5