Earnings Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Income from continuing operations	$ 347.5	$ 155.6
Loss from discontinued operations	0.0	(1.0)
Net Income Attributable to Air Products	$ 347.5	$ 154.6
Weighted average common shares — Basic	219.9	218.9
Employee stock option and other award plans	1.1	1.5
Weighted average common shares — Diluted	221.0	220.4
Earnings Per Share, Basic [Abstract]
Income from continuing operations (in dollars per share)	$ 1.58	$ 0.71
Income (Loss) from discontinued operations (in dollars per share)	0	0
Net Income Attributable to Air Products (in dollars per share)	1.58	0.71
Earnings Per Share, Diluted [Abstract]
Income from continuing operations (in dollars per share)	1.57	0.70
Income (Loss) from discontinued operations (in dollars per share)	0	0
Net Income Attributable to Air Products (in dollars per share)	$ 1.57	$ 0.70