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, 2017	$ 10,185.5	$ 249.4	$ 1,001.1	$ 12,846.6	$ (1,847.4)	$ (2,163.5)	$ 10,086.2	$ 99.3
Stockholders' Equity [Roll Forward]
Net income	585.3			571.0			571.0	14.3
Other comprehensive income (loss)	316.2				312.1		312.1	4.1
Dividends on common stock	(449.1)			(449.1)			(449.1)
Dividends to noncontrolling interests	(10.6)							(10.6)
Share-based compensation	21.8		21.8				21.8
Issuance of treasury shares for stock option and award plans	40.1		(12.3)			52.4	40.1
Other equity transactions	4.0		0.6	(1.9)			(1.3)	5.3
Ending balance at Mar. 31, 2018	10,693.2	249.4	1,011.2	12,966.6	(1,535.3)	(2,111.1)	10,580.8	112.4
Beginning balance at Dec. 31, 2017	10,321.2	249.4	998.1	12,792.3	(1,695.6)	(2,128.9)	10,215.3	105.9
Stockholders' Equity [Roll Forward]
Net income	423.6			416.4			416.4	7.2
Other comprehensive income (loss)	162.5				160.3		160.3	2.2
Dividends on common stock	(241.1)			(241.1)			(241.1)
Dividends to noncontrolling interests	(2.9)							(2.9)
Share-based compensation	10.7		10.7				10.7
Issuance of treasury shares for stock option and award plans	20.2		2.4			17.8	20.2
Other equity transactions	(1.0)		0.0	(1.0)			(1.0)	0.0
Ending balance at Mar. 31, 2018	10,693.2	249.4	1,011.2	12,966.6	(1,535.3)	(2,111.1)	10,580.8	112.4
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	790.5			768.8			768.8	21.7
Other comprehensive income (loss)	1.3				(2.9)		(2.9)	4.2
Dividends on common stock	(497.5)			(497.5)			(497.5)
Dividends to noncontrolling interests	(7.0)							(7.0)
Share-based compensation	20.7		20.7				20.7
Issuance of treasury shares for stock option and award plans	39.7		(0.9)			40.6	39.7
Cumulative change in accounting principle	(17.1)			(17.1)			(17.1)
Other equity transactions	(3.5)		(1.4)	(2.1)			(3.5)
Ending 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
Beginning balance at Dec. 31, 2018	11,203.4	249.4	1,030.4	13,497.9	(1,811.2)	(2,083.6)	10,882.9	320.5
Stockholders' Equity [Roll Forward]
Net income	433.5			421.3			421.3	12.2
Other comprehensive income (loss)	71.5				66.4		66.4	5.1
Dividends on common stock	(255.9)			(255.9)			(255.9)
Dividends to noncontrolling interests	(0.1)							(0.1)
Share-based compensation	11.8		11.8				11.8
Issuance of treasury shares for stock option and award plans	41.7		6.7			35.0	41.7
Other equity transactions	(2.5)		(1.2)	(1.3)			(2.5)	0.0
Ending 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