Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales		$ (12,037.3)	$ (12,100.6)	$ (12,600.0)
Cost of sales		8,256.0	8,168.7	8,833.0
Interest expense		214.0	218.8	177.5
Other non-operating income (expense), net		(2.6)	73.8	39.0
Gain on sale of business		(67.3)	(1,575.6)	0.0
Business and asset actions		3,747.0	57.0	244.6
Other income (expense), net	$ (7.4)	8.0	13.9	(7.4)
Net income (loss) attributable to Air Products		394.5	(3,828.2)	(2,300.2)
Other income (expense), net		(110.1)	(58.2)	(34.8)
Reclassification out of Accumulated Other Comprehensive Income | (Gain) Loss on Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales		(0.2)	0.0	(0.5)
Cost of sales		6.0	1.9	3.7
Interest expense		(0.1)	2.3	3.5
Other non-operating income (expense), net		35.5	(37.9)	(50.6)
Net income (loss) attributable to Air Products		41.2	(33.7)	(43.9)
Reclassification out of Accumulated Other Comprehensive Income | Currency Translation Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain on sale of business		0.1	(1.5)	0.0
Business and asset actions		1.0	0.0	(0.3)
Other income (expense), net		4.6	0.0	0.0
Net income (loss) attributable to Air Products		5.7	(1.5)	(0.3)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Postretirement Benefits
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income (loss) attributable to Air Products		$ 46.0	$ 55.9	$ 53.8