Business Segment and Geographic Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Sales		$ 12,600.0	$ 12,698.6	$ 10,323.0
Operating income (loss)		2,494.6	2,338.8	2,281.4
Depreciation and amortization		1,358.3	1,338.2	1,321.3
Equity affiliates' income		604.3	481.5	294.1
Expenditures for long-lived assets		4,626.4	2,926.5	2,464.2
Investment in net assets of and advances to equity affiliates		4,617.8	3,353.8
Total assets	[1]	32,002.5	27,192.6
Operating Segments
Segment Reporting Information [Line Items]
Sales		12,600.0	12,698.6	10,323.0
Operating income (loss)		2,739.2	2,412.5	2,267.8
Depreciation and amortization		1,358.3	1,338.2	1,321.3
Equity affiliates' income		604.3	496.3	294.1
Expenditures for long-lived assets		4,626.4	2,926.5	2,464.2
Investment in net assets of and advances to equity affiliates		4,617.8	3,353.8
Total assets		32,002.5	27,192.6
Americas | Operating Segments
Segment Reporting Information [Line Items]
Sales		5,369.3	5,368.9	4,167.6
Operating income (loss)		1,439.7	1,174.4	1,065.5
Depreciation and amortization		649.3	629.5	611.9
Equity affiliates' income		109.2	98.2	112.5
Expenditures for long-lived assets		2,033.7	1,353.1	909.6
Investment in net assets of and advances to equity affiliates		476.9	434.4
Total assets		9,927.5	8,237.7
Asia | Operating Segments
Segment Reporting Information [Line Items]
Sales		3,216.1	3,143.3	2,920.8
Operating income (loss)		906.5	898.3	838.3
Depreciation and amortization		433.5	436.5	444.4
Equity affiliates' income		29.7	22.1	35.9
Expenditures for long-lived assets		663.4	779.2	792.3
Investment in net assets of and advances to equity affiliates		285.2	268.9
Total assets		7,009.6	6,968.7
Europe | Operating Segments
Segment Reporting Information [Line Items]
Sales		2,963.1	3,086.1	2,345.6
Operating income (loss)		663.4	503.4	529.4
Depreciation and amortization		196.2	195.2	204.5
Equity affiliates' income		102.5	78.2	62.8
Expenditures for long-lived assets		482.4	312.6	300.3
Investment in net assets of and advances to equity affiliates		504.9	435.0
Total assets		4,649.8	3,645.1
Middle East and India | Operating Segments
Segment Reporting Information [Line Items]
Sales		162.5	129.5	99.3
Operating income (loss)		16.9	21.1	28.0
Depreciation and amortization		27.5	26.9	25.3
Equity affiliates' income		349.8	293.9	76.4
Expenditures for long-lived assets		1,312.7	271.6	71.0
Investment in net assets of and advances to equity affiliates		3,265.2	2,143.3
Total assets		5,708.4	2,980.7
Corporate and other | Operating Segments
Segment Reporting Information [Line Items]
Sales		889.0	970.8	789.7
Operating income (loss)		(287.3)	(184.7)	(193.4)
Depreciation and amortization		51.8	50.1	35.2
Equity affiliates' income		13.1	3.9	6.5
Expenditures for long-lived assets		134.2	210.0	$ 391.0
Investment in net assets of and advances to equity affiliates		85.6	72.2
Total assets		$ 4,707.2	$ 5,360.4

[1] Includes balances associated with a consolidated variable interest entity ("VIE"), including amounts reflected in "Total Assets" that can only be used to settle obligations of the VIE of $2,256.8 and $519.7 as of 30 September 2023 and 30 September 2022, respectively, as well as liabilities of the VIE reflected within "Total Liabilities" for which creditors do not have recourse to the general credit of Air Products of $1,461.1 and $506.8 as of 30 September 2023 and 30 September 2022, respectively. Refer to Note 3, Variable Interest Entities, for additional information.