Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	$ (2,994.2)	$ (2,375.2)
Cost of sales	(2,223.6)	(1,632.4)
Interest expense	(30.5)	(36.7)
Other non-operating income (expense), net	(22.6)	(18.6)
Net Income Attributable to Air Products	(560.4)	(482.0)
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	0.3	0.1
Cost of sales	(0.1)	0.1
Interest expense	0.9	0.9
Other non-operating income (expense), net	17.6	(2.4)
Net Income Attributable to Air Products	18.7	(1.3)
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	$ 16.0	$ 18.3