Consolidated Statements of Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Air Products Shareholders' Equity	Non-controlling Interests
Beginning balance at Sep. 30, 2019	$ 11,388.3	$ 249.4	$ 1,070.9	$ 14,138.4	$ (2,375.6)	$ (2,029.5)	$ 11,053.6	$ 334.7
Stockholders' Equity [Roll Forward]
Net income	488.9			475.6			475.6	13.3
Other comprehensive income (loss)	302.2				287.0		287.0	15.2
Dividends on common stock	(256.0)			(256.0)			(256.0)
Dividends to noncontrolling interests	(1.3)							(1.3)
Share-based compensation	13.9		13.9				13.9
Issuance of treasury shares for stock option and award plans	(12.4)		(18.5)			6.1	(12.4)
Investments by noncontrolling interests	11.9							11.9
Other equity transactions	(5.7)		(4.6)	(1.1)			(5.7)	0.0
Ending balance at Dec. 31, 2019	11,929.8	249.4	1,061.7	14,356.9	(2,088.6)	(2,023.4)	11,556.0	373.8
Beginning balance at Sep. 30, 2020	12,443.1	249.4	1,094.8	14,875.7	(2,140.1)	(2,000.0)	12,079.8	363.3
Stockholders' Equity [Roll Forward]
Net income	486.7			482.0			482.0	4.7
Other comprehensive income (loss)	446.5				426.8		426.8	19.7
Dividends on common stock	(296.5)			(296.5)			(296.5)
Share-based compensation	10.3		10.3				10.3
Issuance of treasury shares for stock option and award plans	(17.0)		(21.0)			4.0	(17.0)
Investments by noncontrolling interests	0.6							0.6
Other equity transactions	(1.8)		(1.1)	(0.7)			(1.8)	0.0
Ending balance at Dec. 31, 2020	$ 13,071.9	$ 249.4	$ 1,083.0	$ 15,060.5	$ (1,713.3)	$ (1,996.0)	$ 12,683.6	$ 388.3