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	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
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	1,496.1			1,488.7			1,488.7	7.4
Other comprehensive income (loss)	494.9				458.2		458.2	36.7
Dividends on common stock	(960.5)			(960.5)			(960.5)
Dividends to noncontrolling interests	(4.6)							(4.6)
Share-based compensation	32.9		32.9				32.9
Issuance of treasury shares for stock option and award plans	(11.7)		(21.7)			10.0	(11.7)
Investments by noncontrolling interests	10.0							10.0
Purchase of noncontrolling interests	(5.3)		(1.2)				(1.2)	(4.1)
Other equity transactions	(3.3)		0.4	(3.7)			(3.3)	0.0
Ending balance at Jun. 30, 2021	13,491.6	249.4	1,105.2	15,400.2	(1,681.9)	(1,990.0)	13,082.9	408.7
Beginning balance at Mar. 31, 2021	13,134.8	249.4	1,094.4	15,200.0	(1,824.4)	(1,993.2)	12,726.2	408.6
Stockholders' Equity [Roll Forward]
Net income	532.3			533.6			533.6	(1.3)
Other comprehensive income (loss)	143.9				142.5		142.5	1.4
Dividends on common stock	(332.0)			(332.0)			(332.0)
Dividends to noncontrolling interests	(1.2)							(1.2)
Share-based compensation	10.6		10.6				10.6
Issuance of treasury shares for stock option and award plans	3.2		0.0			3.2	3.2
Investments by noncontrolling interests	1.3							1.3
Other equity transactions	(1.3)		0.2	(1.4)			(1.2)	(0.1)
Ending balance at Jun. 30, 2021	$ 13,491.6	$ 249.4	$ 1,105.2	$ 15,400.2	$ (1,681.9)	$ (1,990.0)	$ 13,082.9	$ 408.7