Earnings per Share (Schedule of Earnings per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share
Income from continuing operations	$ 344.5	$ 318.8	$ 290.0	$ 324.6	$ 102.5	$ 314.0	$ 283.5	$ 287.1	$ 1,277.9	$ 987.1	$ 1,004.2
Income from discontinued operations	0.0	0.0	0.0	0.0	1.5	0.0	0.0	3.1	0.0	4.6	(10.0)
Net Income Attributable to Air Products	$ 344.5	$ 318.8	$ 290.0	$ 324.6	$ 104.0	$ 314.0	$ 283.5	$ 290.2	$ 1,277.9	$ 991.7	$ 994.2
Weighted average number of common shares outstanding									214.9	212.7	209.7
Employee stock option and other award plans									2.4	2.5	2.6
Weighted average number of common shares outstanding assuming dilution									217.3	215.2	212.3
Income from Continuing Operations, Basic	$ 1.6	$ 1.48	$ 1.35	$ 1.52	$ 0.48	$ 1.47	$ 1.33	$ 1.36	$ 5.95	$ 4.64	$ 4.79
Income (loss) from Discontinued Operations, Basic	0	0	0	0	0.01	0	0	0.01	0	0.02	(0.05)
Net Income Attributable to Air Products	1.6	1.48	1.35	1.52	0.49	1.47	1.33	1.37	5.95	4.66	4.74
Income from Continuing Operations, Diluted	1.58	1.47	1.33	1.5	0.47	1.46	1.32	1.34	5.88	4.59	4.73
Income from Discontinued Operations, Diluted	0	0	0	0	0.01	0	0	0.01	0	0.02	(0.05)
Net Income Attributable to Air Products	$ 1.58	$ 1.47	$ 1.33	$ 1.5	$ 0.48	$ 1.46	$ 1.32	$ 1.35	$ 5.88	$ 4.61	$ 4.68