Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	$ (12,600.0)	$ (12,698.6)	$ (10,323.0)
Cost of sales	8,833.0	9,338.5	7,186.1
Interest expense	177.5	128.0	141.8
Other non-operating income (expense), net	39.0	(62.4)	(73.7)
Business and asset actions	(244.6)	(73.7)	0.0
Income from discontinued operations, net of tax	(7.4)	(12.6)	(70.3)
Net income (loss) attributable to Air Products	(2,300.2)	(2,256.1)	(2,099.1)
Other income (expense), net	(34.8)	(55.9)	(52.8)
Reclassification out of Accumulated Other Comprehensive Income | (Gain) Loss on Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	(0.5)	0.5	(0.6)
Cost of sales	3.7	(0.4)	(0.3)
Interest expense	3.5	3.6	3.5
Other non-operating income (expense), net	(50.6)	87.7	40.9
Net income (loss) attributable to Air Products	(43.9)	91.4	43.5
Reclassification out of Accumulated Other Comprehensive Income | Currency Translation Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Business and asset actions	(0.3)	5.1	0.0
Income from discontinued operations, net of tax	0.0	2.2	0.0
Net income (loss) attributable to Air Products	(0.3)	7.3	0.0
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	$ 53.8	$ 64.8	$ 74.6