Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Sep. 30, 2025
Segment Reporting [Line Items]
Sales		$ 3,161.0	$ 3,022.7	$ 9,435.3	$ 8,870.4
Cost of sales		(2,125.0)	(2,040.1)	(6,416.9)	(6,110.5)
Selling and administrative expense		(219.1)	(222.6)	(675.0)	(687.0)
Operating income (loss)		(2,097.1)	790.6	(609.9)	(893.8)
Depreciation and amortization				1,131.1	1,151.4
Equity affiliates' income (loss)		205.2	167.6	556.8	463.7
Investment in net assets of and advances to equity affiliates		5,577.4		5,577.4		$ 5,366.1
Total assets	[1]	40,445.6		40,445.6		41,059.5
Operating Segments
Segment Reporting [Line Items]
Sales		3,161.0	3,022.7	9,435.3	8,870.4
Cost of sales		(2,125.0)	(2,040.1)	(6,416.9)	(6,110.5)
Selling and administrative expense		(219.1)	(222.6)	(675.0)	(687.0)
Other segment items		(6.6)	(18.9)	(23.9)	(27.0)
Operating income (loss)		810.3	741.1	2,319.5	2,045.9
Depreciation and amortization		385.4	401.0	1,131.1	1,151.4
Equity affiliates' income (loss)		205.2	167.6	556.8	470.5
Expenditures for long-lived assets				3,354.5	5,504.9
Investment in net assets of and advances to equity affiliates		5,577.4		5,577.4		5,366.1
Total assets		40,445.6		40,445.6		41,059.5
Segment Reconciling Items
Segment Reporting [Line Items]
Project exit-related impairment of equity method investment					6.8
Americas | Operating Segments
Segment Reporting [Line Items]
Sales		1,321.4	1,261.0	4,047.0	3,835.8
Cost of sales		(873.7)	(840.3)	(2,719.8)	(2,568.9)
Selling and administrative expense		(54.7)	(52.0)	(163.7)	(156.2)
Other segment items		2.4	5.4	9.6	17.3
Operating income (loss)		395.4	374.1	1,173.1	1,128.0
Depreciation and amortization		181.4	192.4	525.0	544.2
Equity affiliates' income (loss)		56.2	37.8	163.7	104.1
Expenditures for long-lived assets				1,410.6	2,110.8
Investment in net assets of and advances to equity affiliates		626.5		626.5		555.2
Total assets		10,408.3		10,408.3		12,058.7
Asia | Operating Segments
Segment Reporting [Line Items]
Sales		886.0	810.0	2,550.1	2,401.2
Cost of sales		(599.0)	(567.9)	(1,733.8)	(1,694.4)
Selling and administrative expense		(33.2)	(29.0)	(94.2)	(90.5)
Other segment items		2.6	3.7	6.6	8.3
Operating income (loss)		256.4	216.8	728.7	624.6
Depreciation and amortization		117.2	126.7	346.7	381.4
Equity affiliates' income (loss)		12.9	9.5	38.4	30.3
Expenditures for long-lived assets				313.9	296.2
Investment in net assets of and advances to equity affiliates		350.0		350.0		331.3
Total assets		6,869.5		6,869.5		6,712.2
Europe | Operating Segments
Segment Reporting [Line Items]
Sales		815.7	770.5	2,386.7	2,195.1
Cost of sales		(520.5)	(480.3)	(1,521.1)	(1,403.7)
Selling and administrative expense		(65.9)	(65.6)	(202.6)	(186.7)
Other segment items		1.4	0.6	2.8	2.5
Operating income (loss)		230.7	225.2	665.8	607.2
Depreciation and amortization		72.2	64.9	214.5	176.2
Equity affiliates' income (loss)		32.6	29.7	87.9	75.6
Expenditures for long-lived assets				563.5	728.1
Investment in net assets of and advances to equity affiliates		669.3		669.3		649.9
Total assets		7,170.2		7,170.2		6,916.8
Middle East and India | Operating Segments
Segment Reporting [Line Items]
Sales		34.8	38.3	94.3	103.9
Cost of sales		(22.0)	(26.0)	(63.4)	(84.0)
Selling and administrative expense		(5.3)	(5.2)	(14.9)	(19.3)
Other segment items		0.5	1.0	2.4	4.0
Operating income (loss)		8.0	8.1	18.4	4.6
Depreciation and amortization		5.8	6.8	18.0	19.7
Equity affiliates' income (loss)		101.1	86.0	264.8	249.2
Expenditures for long-lived assets				984.1	2,285.1
Investment in net assets of and advances to equity affiliates		3,813.1		3,813.1		3,713.2
Total assets		11,887.2		11,887.2		10,919.4
Corporate and other | Operating Segments
Segment Reporting [Line Items]
Sales		103.1	142.9	357.2	334.4
Cost of sales		(109.8)	(125.6)	(378.8)	(359.5)
Selling and administrative expense		(60.0)	(70.8)	(199.6)	(234.3)
Other segment items		(13.5)	(29.6)	(45.3)	(59.1)
Operating income (loss)		(80.2)	(83.1)	(266.5)	(318.5)
Depreciation and amortization		8.8	10.2	26.9	29.9
Equity affiliates' income (loss)		2.4	$ 4.6	2.0	11.3
Expenditures for long-lived assets				82.4	$ 84.7
Investment in net assets of and advances to equity affiliates		118.5		118.5		116.5
Total assets		$ 4,110.4		$ 4,110.4		$ 4,452.4

[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 $8,138.4 and $7,134.7 as of 30 June 2026 and 30 September 2025, 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 $5,474.3 and $4,937.7 as of 30 June 2026 and 30 September 2025, respectively. Refer to Note 3, Variable Interest Entities, for additional information regarding the NEOM Green Hydrogen Company joint venture.