Business Segment and Geographic Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Sales		$ 12,037.3	$ 12,100.6	$ 12,600.0
Cost of sales		(8,256.0)	(8,168.7)	(8,833.0)
Selling and administrative expense		(906.1)	(942.4)	(957.0)
Operating income (loss)		(877.0)	4,466.1	2,494.6
Depreciation and amortization		1,564.2	1,451.1	1,358.3
Equity affiliates' income		647.7	647.7	604.3
Investment in net assets of and advances to equity affiliates		5,366.1	4,792.5
Total assets	[1]	41,059.5	39,574.6
Project exit-related impairment of equity method investment		6.8	0.0	0.0
Operating Segments
Segment Reporting Information [Line Items]
Sales		12,037.3	12,100.6	12,600.0
Cost of sales		(8,256.0)	(8,168.7)	(8,833.0)
Selling and administrative expense		(906.1)	(942.4)	(957.0)
Other segment items		(17.5)	(42.0)	(70.8)
Operating income (loss)		2,857.7	2,947.5	2,739.2
Depreciation and amortization		1,564.2	1,451.1	1,358.3
Equity affiliates' income		654.5	647.7	604.3
Investment in net assets of and advances to equity affiliates		5,366.1	4,792.5
Total assets		41,059.5	39,574.6
Expenditures for long-lived assets		7,022.6	6,796.7	4,626.4
Segment Reconciling Items
Segment Reporting Information [Line Items]
Project exit-related impairment of equity method investment		6.8
Americas | Operating Segments
Segment Reporting Information [Line Items]
Sales		5,125.9	5,040.1	5,369.3
Cost of sales		(3,423.5)	(3,284.8)	(3,715.5)
Selling and administrative expense		(206.6)	(212.5)	(222.4)
Other segment items		23.8	22.3	8.3
Operating income (loss)		1,519.6	1,565.1	1,439.7
Depreciation and amortization		732.1	699.3	649.3
Equity affiliates' income		157.0	158.8	109.2
Investment in net assets of and advances to equity affiliates		555.2	472.9
Total assets		12,058.7	12,383.8
Expenditures for long-lived assets		2,610.7	2,733.1	2,033.7
Asia | Operating Segments
Segment Reporting Information [Line Items]
Sales		3,271.0	3,224.3	3,216.1
Cost of sales		(2,323.3)	(2,255.8)	(2,194.6)
Selling and administrative expense		(118.3)	(122.0)	(123.7)
Other segment items		21.7	12.7	8.7
Operating income (loss)		851.1	859.2	906.5
Depreciation and amortization		518.9	471.0	433.5
Equity affiliates' income		42.3	32.9	29.7
Investment in net assets of and advances to equity affiliates		331.3	322.9
Total assets		6,712.2	7,436.5
Expenditures for long-lived assets		406.6	574.8	663.4
Europe | Operating Segments
Segment Reporting Information [Line Items]
Sales		2,984.5	2,823.4	2,963.1
Cost of sales		(1,893.2)	(1,783.7)	(2,080.1)
Selling and administrative expense		(254.0)	(243.2)	(224.0)
Other segment items		7.4	13.5	4.4
Operating income (loss)		844.7	810.0	663.4
Depreciation and amortization		247.4	207.1	196.2
Equity affiliates' income		101.9	88.1	102.5
Investment in net assets of and advances to equity affiliates		649.9	573.8
Total assets		6,916.8	5,849.2
Expenditures for long-lived assets		1,010.6	865.2	482.4
Middle East and India | Operating Segments
Segment Reporting Information [Line Items]
Sales		135.9	134.4	162.5
Cost of sales		(107.4)	(101.0)	(120.0)
Selling and administrative expense		(24.1)	(28.2)	(26.9)
Other segment items		5.2	0.7	1.3
Operating income (loss)		9.6	5.9	16.9
Depreciation and amortization		25.9	26.6	27.5
Equity affiliates' income		340.9	347.5	349.8
Investment in net assets of and advances to equity affiliates		3,713.2	3,317.7
Total assets		10,919.4	8,477.4
Expenditures for long-lived assets		2,868.6	2,517.5	1,312.7
Corporate and other | Operating Segments
Segment Reporting Information [Line Items]
Sales		520.0	878.4	889.0
Cost of sales		(508.6)	(743.4)	(722.8)
Selling and administrative expense		(303.1)	(336.5)	(360.0)
Other segment items		(75.6)	(91.2)	(93.5)
Operating income (loss)		(367.3)	(292.7)	(287.3)
Depreciation and amortization		39.9	47.1	51.8
Equity affiliates' income		12.4	20.4	13.1
Investment in net assets of and advances to equity affiliates		116.5	105.2
Total assets		4,452.4	5,427.7
Expenditures for long-lived assets		$ 126.1	$ 106.1	$ 134.2

[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 $7,134.7 and $4,393.9 as of 30 September 2025 and 2024, 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 $4,937.7 and $3,473.4 as of 30 September 2025 and 2024, respectively. Refer to Note 3, Variable Interest Entities, for additional information regarding the NEOM Green Hydrogen Company joint venture.