Earnings per Share (Schedule of Earnings per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Income from continuing operations	$ 251.6	$ 280.9
Income from discontinued operations	48.2	82.7
Net Income Attributable to Air Products	$ 299.8	$ 363.6
Weighted average common shares — Basic (in shares)	217.7	215.8
Effect of dilutive securities - Employee stock option and other award plans (in shares)	2.0	1.8
Weighted average common shares — Diluted (in shares)	219.7	217.6
Earnings Per Share, Basic [Abstract]
Income from continuing operations, basic (in dollars per share)	$ 1.16	$ 1.30
Income from discontinued operations, basic (in dollars per share)	0.22	0.38
Net Income Attributable to Air Products (in dollars per share)	1.38	1.68
Earnings Per Share, Diluted [Abstract]
Income from continuing operations, diluted (in dollars per share)	1.15	1.29
Income from discontinued operations, diluted (in dollars per share)	0.22	0.38
Net Income Attributable to Air Products (in dollars per share)	$ 1.37	$ 1.67