Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 16,129.1	$ 14,517.4	$ 15,660.3	$ 13,702.4
Other comprehensive income (loss) before reclassifications	(141.5)		78.0
Amounts reclassified from AOCL	48.4		19.9
Other Comprehensive Income (Loss), Net of Tax, Total	(93.1)	56.3	97.9	636.8
Amount attributable to noncontrolling interests	62.5	1.3	(75.6)	14.0
Ending balance	16,334.9	14,690.2	16,334.9	14,690.2
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	11.9		61.1
Other comprehensive income (loss) before reclassifications	82.3		(78.8)
Amounts reclassified from AOCL	34.8		(7.4)
Other Comprehensive Income (Loss), Net of Tax, Total	117.1		(86.2)
Amount attributable to noncontrolling interests	75.6		(78.5)
Ending balance	53.4		53.4
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,548.7)		(1,913.3)
Other comprehensive income (loss) before reclassifications	(223.8)		156.8
Amounts reclassified from AOCL	0.0		0.0
Other Comprehensive Income (Loss), Net of Tax, Total	(223.8)		156.8
Amount attributable to noncontrolling interests	(13.2)		2.8
Ending balance	(1,759.3)		(1,759.3)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(583.5)		(597.2)
Other comprehensive income (loss) before reclassifications	0.0		0.0
Amounts reclassified from AOCL	13.6		27.3
Other Comprehensive Income (Loss), Net of Tax, Total	13.6		27.3
Amount attributable to noncontrolling interests	0.1		0.1
Ending balance	(570.0)		(570.0)
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,120.3)	(2,218.3)	(2,449.4)	(2,786.1)
Other Comprehensive Income (Loss), Net of Tax, Total	(155.6)	55.0	173.5	622.8
Ending balance	$ (2,275.9)	$ (2,163.3)	$ (2,275.9)	$ (2,163.3)