Consolidated Statements of Equity - 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, 2014	$ 7,521.4	$ 249.4	$ 842.0	$ 9,993.2	$ (1,241.9)	$ (2,476.9)	$ 7,365.8	$ 155.6
Stockholders' Equity [Roll Forward]
Net income	1,306.1			1,277.9			1,277.9	28.2
Other comprehensive income (loss)	(895.0)				(884.0)		(884.0)	(11.0)
Cash dividends	(687.9)			(687.9)			(687.9)
Share-based compensation expense	43.7		43.7				43.7
Issuance of treasury shares for stock option and award plans	102.2		(15.1)			117.3	102.2
Tax benefit of stock option and award plans	32.0		32.0				32.0
Dividends to noncontrolling interests	(38.0)							(38.0)
Purchase of noncontrolling interests	(0.5)		(0.3)				(0.3)	(0.2)
Other	(2.9)		2.4	(2.8)			(0.4)	(2.5)
Ending Balance at Sep. 30, 2015	7,381.1	249.4	904.7	10,580.4	(2,125.9)	(2,359.6)	7,249.0	132.1
Stockholders' Equity [Roll Forward]
Net income	661.5			631.1			631.1	30.4
Other comprehensive income (loss)	(257.6)				(262.4)		(262.4)	4.8
Cash dividends	(733.7)			(733.7)			(733.7)
Share-based compensation expense	37.6		37.6				37.6
Issuance of treasury shares for stock option and award plans	127.1		(5.5)			132.6	127.1
Tax benefit of stock option and award plans	33.2		33.2				33.2
Dividends to noncontrolling interests	(33.6)							(33.6)
Other	(2.2)			(2.3)			(2.3)	0.1
Ending Balance at Sep. 30, 2016	7,213.4	249.4	970.0	10,475.5	(2,388.3)	(2,227.0)	7,079.6	133.8
Stockholders' Equity [Roll Forward]
Net income	3,021.2			3,000.4			3,000.4	20.8
Other comprehensive income (loss)	533.1				529.4		529.4	3.7
Cash dividends	(808.5)			(808.5)			(808.5)
Share-based compensation expense	40.7		40.7				40.7
Issuance of treasury shares for stock option and award plans	53.9		(9.6)			63.5	53.9
Dividends to noncontrolling interests	(28.0)							(28.0)
Spin-off of Versum	152.6			175.0	11.5		186.5	(33.9)
Cumulative change in accounting principle	8.8			8.8			8.8
Other	(1.7)			(4.6)			(4.6)	2.9
Ending 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