Earnings per Share (Schedule of Earnings per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Income from continuing operations	$ 304.4	$ 278.9	$ 556.0	$ 559.8
Income (Loss) from discontinued operations	1,825.6	(752.2)	1,873.8	(669.5)
Net Income (Loss) Attributable to Air Products	$ 2,130.0	$ (473.3)	$ 2,429.8	$ (109.7)
Weighted average common shares — Basic (in shares)	217.9	216.1	217.8	215.9
Effect of dilutive securities - Employee stock option and other award plans (in shares)	1.8	1.8	1.8	1.9
Weighted average common shares — Diluted (in shares)	219.7	217.9	219.6	217.8
Earnings Per Share, Basic [Abstract]
Income from continuing operations, basic (in dollars per share)	$ 1.40	$ 1.29	$ 2.55	$ 2.59
Income from discontinued operations, basic (in dollars per share)	8.38	(3.48)	8.61	(3.10)
Net Income Attributable to Air Products (in dollars per share)	9.78	(2.19)	11.16	(0.51)
Earnings Per Share, Diluted [Abstract]
Income from continuing operations, diluted (in dollars per share)	1.39	1.28	2.53	2.57
Income from discontinued operations, diluted (in dollars per share)	8.31	(3.45)	8.53	(3.08)
Net Income Attributable to Air Products (in dollars per share)	$ 9.70	$ (2.17)	$ 11.06	$ (0.51)