Earnings Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Income from continuing operations	$ 488.0	$ 430.7	$ 1,256.8	$ 1,002.7
Income from discontinued operations	0.0	43.2	0.0	42.2
Net Income Attributable to Air Products	$ 488.0	$ 473.9	$ 1,256.8	$ 1,044.9
Weighted average common shares — Basic	220.6	219.5	220.2	219.3
Employee stock option and other award plans	1.3	1.4	1.2	1.4
Weighted average common shares — Diluted	221.9	220.9	221.4	220.7
Earnings Per Share, Basic [Abstract]
Income from continuing operations (in dollars per share)	$ 2.21	$ 1.96	$ 5.71	$ 4.57
Income (Loss) from discontinued operations (in dollars per share)	0	0.20	0	0.19
Net Income Attributable to Air Products (in dollars per share)	2.21	2.16	5.71	4.76
Earnings Per Share, Diluted [Abstract]
Income from continuing operations (in dollars per share)	2.20	1.95	5.68	4.54
Income (Loss) from discontinued operations (in dollars per share)	0	0.20	0	0.19
Net Income Attributable to Air Products (in dollars per share)	$ 2.20	$ 2.15	$ 5.68	$ 4.73