Summary by Quarter (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2010
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 2,605.8		$ 2,340.1		$ 2,344.3		$ 2,321.5		$ 2,506.2		$ 2,472.0		$ 2,403.0		$ 2,292.5		$ 9,611.7		$ 9,673.7		$ 8,616.1
Gross Profit	682.8		649.3		628.5		599.2		651.4		646.3		654.8		622.9		2,559.8		2,575.4
Net loss on Airgas transaction									0	[1]	0	[1]	5.0	[1]	43.5	[1]	0		48.5		96.0
Business restructuring and cost reduction plans	240.6	[2]	0	[2]	86.8	[2]	0	[2]									327.4	[3]	0	[3]	0	[3]
Gain on previously held equity interest	0	[4]	85.9	[4]	0	[4]	0	[4]									85.9		0		0
Customer Bankruptcy	9.8	[5]	0	[5]	0	[5]	0	[5]									9.8		0		(6.4)
Operating Income	157.9		482.8		287.9		353.8		395.4		387.7		393.8		331.2		1,282.4		1,508.1		1,267.7
Net Income	142.3		492.5		302.2		256.3		339.1		335.0		311.5		275.9		1,193.3		1,261.5		1,054.5
Income from continuing operations attributable to Air Products	137.1		357.2		279.0		225.9		304.2		297.0		285.7		247.4		999.2		1,134.3		941.6
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	1.6		127.3		17.0		22.2		20.6		29.5		18.6		21.2		168.1		89.9		87.5
Net Income Attributable to Air Products	$ 138.7		$ 484.5		$ 296.0		$ 248.1		$ 324.8		$ 326.5		$ 304.3		$ 268.6		$ 1,167.3		$ 1,224.2		$ 1,029.1
Basic Earnings Per Common Share Attributable to Air Products
Income from Continuing Operations, Basic	$ 0.65		$ 1.69		$ 1.32		$ 1.07		$ 1.44		$ 1.40		$ 1.34		$ 1.15		$ 4.73		$ 5.33		$ 4.44
Income from discontinued operations	$ 0.01		$ 0.60		$ 0.08		$ 0.11		$ 0.10		$ 0.14		$ 0.08		$ 0.10		$ 0.80		$ 0.42		$ 0.41
Net Income Attributable to Air Products	$ 0.66		$ 2.29		$ 1.40		$ 1.18		$ 1.54		$ 1.54		$ 1.42		$ 1.25		$ 5.53		$ 5.75		$ 4.85
Diluted Earnings Per Common Share Attributable to Air Products
Income from continuing operations	$ 0.64		$ 1.66		$ 1.30		$ 1.06		$ 1.41		$ 1.37		$ 1.31		$ 1.13		$ 4.66		$ 5.22		$ 4.34
Income from discontinued operations	$ 0.01		$ 0.60		$ 0.08		$ 0.10		$ 0.10		$ 0.13		$ 0.08		$ 0.10		$ 0.78		$ 0.41		$ 0.40
Net Income Attributable to Air Products	$ 0.65		$ 2.26		$ 1.38		$ 1.16		$ 1.51		$ 1.50		$ 1.39		$ 1.23		$ 5.44		$ 5.63		$ 4.74
Dividends per common share	$ 0.64		$ 0.64		$ 0.64		$ 0.58		$ 0.58		$ 0.58		$ 0.58		$ 0.49		$ 2.50		$ 2.23		$ 1.92
Market Price Per Share High	$ 85.83		$ 92.79		$ 92.48		$ 90.20		$ 98.00		$ 96.00		$ 95.00		$ 91.39
Market Price Per Share Low	$ 77.21		$ 76.11		$ 85.60		$ 72.26		$ 74.58		$ 89.18		$ 83.22		$ 80.90

[1]   For additional information, see Note 6, Airgas Transaction.

[2]   For additional information, see Note 4, Business Restructuring and Cost Reduction Plans.

[3] Information about how this charge related to the businesses at the segment level is discussed in Note 4, Business Restructuring and Cost Reduction Plans.

[4]   For additional information, see Note 5, Business Combinations.

[5]   For additional information, see Note 22, Supplemental Information.