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, 2018	$ 11,176.3	$ 249.4	$ 1,029.3	$ 13,409.9	$ (1,741.9)	$ (2,089.2)	$ 10,857.5	$ 318.8
Stockholders' Equity [Roll Forward]
Net income	1,290.7			1,256.8			1,256.8	33.9
Other comprehensive income (loss)	(40.9)				(39.5)		(39.5)	(1.4)
Dividends on common stock	(752.6)			(752.6)			(752.6)
Dividends to noncontrolling interests	(10.0)							(10.0)
Share-based compensation	30.5		30.5				30.5
Issuance of treasury shares for stock option and award plans	57.0		1.5			55.5	57.0
Cumulative change in accounting principle	(17.1)			(17.1)			(17.1)
Other equity transactions	(7.3)		(1.4)	(5.1)			(6.5)	(0.8)
Ending balance at Jun. 30, 2019	11,726.6	249.4	1,059.9	13,891.9	(1,781.4)	(2,033.7)	11,386.1	340.5
Beginning balance at Mar. 31, 2019	11,503.4	249.4	1,047.7	13,662.0	(1,744.8)	(2,048.6)	11,165.7	337.7
Stockholders' Equity [Roll Forward]
Net income	500.2			488.0			488.0	12.2
Other comprehensive income (loss)	(42.2)				(36.6)		(36.6)	(5.6)
Dividends on common stock	(255.1)			(255.1)			(255.1)
Dividends to noncontrolling interests	(3.0)							(3.0)
Share-based compensation	9.8		9.8				9.8
Issuance of treasury shares for stock option and award plans	17.3		2.4			14.9	17.3
Other equity transactions	(3.8)		0.0	(3.0)			(3.0)	(0.8)
Ending balance at Jun. 30, 2019	11,726.6	249.4	1,059.9	13,891.9	(1,781.4)	(2,033.7)	11,386.1	340.5
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	1,436.4			1,399.9			1,399.9	36.5
Other comprehensive income (loss)	7.7				22.5		22.5	(14.8)
Dividends on common stock	(847.9)			(847.9)			(847.9)
Dividends to noncontrolling interests	(4.5)							(4.5)
Share-based compensation	34.5		34.5				34.5
Issuance of treasury shares for stock option and award plans	5.0		(16.1)			21.1	5.0
Investments by noncontrolling interests	11.9							11.9
Other equity transactions	(8.0)		(4.5)	(3.8)			(8.3)	0.3
Ending balance at Jun. 30, 2020	12,023.4	249.4	1,084.8	14,686.6	(2,353.1)	(2,008.4)	11,659.3	364.1
Beginning balance at Mar. 31, 2020	11,723.7	249.4	1,074.6	14,537.2	(2,478.2)	(2,011.1)	11,371.9	351.8
Stockholders' Equity [Roll Forward]
Net income	457.1			446.5			446.5	10.6
Other comprehensive income (loss)	126.9				125.1		125.1	1.8
Dividends on common stock	(296.0)			(296.0)			(296.0)
Dividends to noncontrolling interests	(0.1)							(0.1)
Share-based compensation	9.9		9.9				9.9
Issuance of treasury shares for stock option and award plans	2.8		0.1			2.7	2.8
Other equity transactions	(0.9)		0.2	(1.1)			(0.9)	0.0
Ending balance at Jun. 30, 2020	$ 12,023.4	$ 249.4	$ 1,084.8	$ 14,686.6	$ (2,353.1)	$ (2,008.4)	$ 11,659.3	$ 364.1