Business Segment Information (Schedule of Segment Reporting Information) (Details) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) segment	Jun. 30, 2024 USD ($)	Sep. 30, 2024 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment				2
Sales		$ 3,022.7	$ 2,985.5	$ 8,870.4	$ 8,913.1
Operating income (loss)		790.6	737.6	(893.8)	2,041.7
Depreciation and amortization				1,151.4	1,070.3
Equity affiliates' income		167.6	168.9	463.7	470.6
Total Assets	[1]	41,659.1		41,659.1		$ 39,574.6
Operating Segments
Segment Reporting Information [Line Items]
Sales		3,022.7	2,985.5	8,870.4	8,913.1
Operating income (loss)		741.1	737.6	2,045.9	2,098.7
Depreciation and amortization		401.0	360.3	1,151.4	1,070.3
Equity affiliates' income		167.6	168.9	470.5	470.6
Total Assets		41,659.1		41,659.1		39,574.6
Americas | Operating Segments
Segment Reporting Information [Line Items]
Sales		1,261.0	1,234.7	3,835.8	3,732.6
Operating income (loss)		374.1	391.1	1,128.0	1,117.4
Depreciation and amortization		192.4	175.6	544.2	519.4
Equity affiliates' income		37.8	37.5	104.1	118.8
Total Assets		11,871.1		11,871.1		12,383.8
Asia | Operating Segments
Segment Reporting Information [Line Items]
Sales		810.0	789.6	2,401.2	2,363.1
Operating income (loss)		216.8	200.1	624.6	614.9
Depreciation and amortization		126.7	115.5	381.4	343.7
Equity affiliates' income		9.5	8.7	30.3	21.2
Total Assets		7,269.9		7,269.9		7,436.5
Europe | Operating Segments
Segment Reporting Information [Line Items]
Sales		770.5	693.4	2,195.1	2,092.5
Operating income (loss)		225.2	204.7	607.2	603.3
Depreciation and amortization		64.9	52.2	176.2	151.2
Equity affiliates' income		29.7	26.3	75.6	58.7
Total Assets		6,871.1		6,871.1		5,849.2
Middle East and India | Operating Segments
Segment Reporting Information [Line Items]
Sales		38.3	32.8	103.9	103.9
Operating income (loss)		8.1	(1.4)	4.6	8.1
Depreciation and amortization		6.8	6.8	19.7	20.1
Equity affiliates' income		86.0	89.2	249.2	256.0
Total Assets		10,510.1		10,510.1		8,477.4
Corporate and other | Operating Segments
Segment Reporting Information [Line Items]
Sales		142.9	235.0	334.4	621.0
Operating income (loss)		(83.1)	(56.9)	(318.5)	(245.0)
Depreciation and amortization		10.2	10.2	29.9	35.9
Equity affiliates' income		4.6	$ 7.2	11.3	$ 15.9
Total Assets		$ 5,136.9		$ 5,136.9		$ 5,427.7

[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 $6,759.1 and $4,393.9 as of 30 June 2025 and 30 September 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 $4,693.9 and $3,473.4 as of 30 June 2025 and 30 September 2024, respectively. Refer to Note 3, Variable Interest Entities, for additional information regarding the NEOM Green Hydrogen Company joint venture.