Consolidated Income Statements - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Sales		$ 10,323.0	$ 8,856.3	$ 8,918.9
Cost of sales		7,186.1	5,858.1	5,975.5
Facility closure		23.2	0.0	29.0
Selling and administrative		828.4	775.9	750.0
Research and development		93.5	83.9	72.9
Cost reduction actions		0.0	0.0	25.5
Gain on exchange with joint venture partner		36.8	0.0	29.1
Company headquarters relocation income (expense)		0.0	33.8	0.0
Other income (expense), net		52.8	65.4	49.3
Operating Income		2,281.4	2,237.6	2,144.4
Equity affiliates' income		294.1	264.8	215.4
Interest expense		141.8	109.3	137.0
Other non-operating income (expense), net		73.7	30.7	66.7
Income From Continuing Operations Before Taxes		2,507.4	2,423.8	2,289.5
Income tax provision		462.8	478.4	480.1
Income From Continuing Operations		2,044.6	1,945.4	1,809.4
Income (Loss) from discontinued operations, net of tax		70.3	(14.3)	0.0
Net Income		2,114.9	1,931.1	1,809.4
Net income attributable to noncontrolling interests of continuing operations		15.8	44.4	49.4
Net Income Attributable to Air Products		2,099.1	1,886.7	1,760.0
Net Income Attributable to Air Products
Net income from continuing operations		2,028.8	1,901.0	1,760.0
Net income (loss) from discontinued operations		70.3	(14.3)	0.0
Net Income Attributable to Air Products		$ 2,099.1	$ 1,886.7	$ 1,760.0
Per Share Data
Basic EPS from continuing operations (in dollars per share)	[1]	$ 9.16	$ 8.59	$ 7.99
Basic EPS from discontinued operations (in dollars per share)	[1]	0.32	(0.06)	0
Basic EPS Attributable to Air Products (in dollars per share)	[1]	9.47	8.53	7.99
Diluted EPS from continuing operations (in dollars per share)	[1]	9.12	8.55	7.94
Diluted EPS from discontinued operations (in dollars per share)	[1]	0.32	(0.06)	0
Diluted EPS Attributable to Air Products (in dollars per share)	[1]	$ 9.43	$ 8.49	$ 7.94
Weighted Average Common Shares (in millions)
Basic		221.6	221.2	220.3
Diluted		222.5	222.3	221.6

[1] Earnings per share ("EPS") is calculated independently for each component and may not sum to total EPS due to rounding.