Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	$ (2,997.4)	$ (3,174.7)
Cost of sales	2,067.2	2,272.3
Interest expense	53.5	41.2
Other non-operating income (expense), net	14.8	0.6
Net Income attributable to Air Products	(609.3)	(572.2)
Reclassification out of Accumulated Other Comprehensive Income | (Gain) Loss on Cash Flow Hedges, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	0.2	0.0
Cost of sales	1.0	1.0
Interest expense	0.8	1.0
Other non-operating income (expense), net	(44.2)	(70.7)
Net Income attributable to Air Products	(42.2)	(68.7)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Postretirement Benefits, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income attributable to Air Products	$ 13.7	$ 11.9