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, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Income from continuing operations	$ 421.3	$ 416.4	$ 768.8	$ 572.0
Loss from discontinued operations	0.0	0.0	0.0	(1.0)
Net Income Attributable to Air Products	$ 421.3	$ 416.4	$ 768.8	$ 571.0
Weighted average common shares — Basic	220.2	219.4	220.0	219.2
Employee stock option and other award plans	1.2	1.4	1.2	1.5
Weighted average common shares — Diluted	221.4	220.8	221.2	220.7
Earnings Per Share, Basic [Abstract]
Income from continuing operations (in dollars per share)	$ 1.91	$ 1.90	$ 3.49	$ 2.61
Income (Loss) from discontinued operations (in dollars per share)	0	0	0	0
Net Income Attributable to Air Products (in dollars per share)	1.91	1.90	3.49	2.61
Earnings Per Share, Diluted [Abstract]
Income from continuing operations (in dollars per share)	1.90	1.89	3.48	2.59
Income (Loss) from discontinued operations (in dollars per share)	0	0	0	0
Net Income Attributable to Air Products (in dollars per share)	$ 1.90	$ 1.89	$ 3.48	$ 2.59