Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales	$ (2,945.1)	$ (2,502.0)	$ (5,939.3)	$ (4,877.2)
Cost of sales	(2,151.6)	(1,745.5)	(4,375.2)	(3,377.9)
Interest expense	(32.3)	(36.1)	(62.8)	(72.8)
Other non-operating income (expense), net	(9.1)	(16.8)	(31.7)	(35.4)
Net Income Attributable to Air Products	(530.5)	(473.1)	(1,090.9)	(955.1)
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	0.1	0.5	0.2
Cost of sales	0.3	(1.4)	0.2	(1.3)
Interest expense	0.9	0.9	1.8	1.8
Other non-operating income (expense), net	24.6	36.4	42.2	34.0
Net Income Attributable to Air Products	26.0	36.0	44.7	34.7
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	$ 15.9	$ 18.3	$ 31.9	$ 36.6