Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	$ (2,930.2)	$ (3,200.1)	$ (5,927.6)	$ (6,374.8)
Cost of sales	1,991.5	2,282.8	4,058.7	4,555.1
Interest expense	59.9	40.9	113.4	82.1
Other non-operating income (expense), net	9.2	13.9	24.0	14.5
Net Income attributable to Air Products	(572.4)	(439.8)	(1,181.7)	(1,012.0)
Business and asset actions	57.0	185.6	57.0	185.6
Reclassification out of Accumulated Other Comprehensive Income | Loss (Gain) on Cash Flow Hedges, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	(0.3)	0.1	(0.1)	0.1
Cost of sales	0.4	1.8	1.4	2.8
Interest expense	0.7	0.7	1.5	1.7
Other non-operating income (expense), net	34.0	3.2	(10.2)	(67.5)
Net Income attributable to Air Products	34.8	5.8	(7.4)	(62.9)
Reclassification out of Accumulated Other Comprehensive Income | Foreign currency translation adjustments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Business and asset actions	0.0	(0.3)	0.0	(0.3)
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	$ 13.6	$ 14.4	$ 27.3	$ 26.3