Earnings Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Income Attributable to Air Products	$ 475.6	$ 347.5
Weighted average common shares — Basic	220.9	219.9
Employee stock option and other award plans	1.3	1.1
Weighted average common shares — Diluted	222.2	221.0
Basic Earnings Per Common Share Attributable to Air Products (in dollars per share)	$ 2.15	$ 1.58
Diluted Earnings Per Common Share Attributable to Air Products (in dollars per share)	$ 2.14	$ 1.57