Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 15,660.3	$ 13,702.4	$ 14,088.0
Other comprehensive income (loss) before reclassifications	254.0	511.4	(1,463.0)
Amounts reclassified from AOCL	20.7	9.6	163.5
Total Other Comprehensive Income (Loss)	274.7	521.0	(1,299.5)
Amount attributable to noncontrolling interests	(147.0)	184.3	(29.3)
Ending balance	18,673.7	15,660.3	13,702.4
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,449.4)	(2,786.1)	(1,515.9)
Total Other Comprehensive Income (Loss)	421.7	336.7	(1,270.2)
Ending balance	(2,027.7)	(2,449.4)	(2,786.1)
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	61.1	(71.9)	(28.3)
Other comprehensive income (loss) before reclassifications	(159.5)	369.2	(120.3)
Amounts reclassified from AOCL	(33.7)	(43.9)	91.4
Total Other Comprehensive Income (Loss)	(193.2)	325.3	(28.9)
Amount attributable to noncontrolling interests	(159.3)	192.3	14.7
Ending balance	27.2	61.1	(71.9)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,913.3)	(2,072.4)	(893.8)
Other comprehensive income (loss) before reclassifications	381.5	151.1	(1,230.5)
Amounts reclassified from AOCL	(1.5)	(0.3)	7.3
Total Other Comprehensive Income (Loss)	380.0	150.8	(1,223.2)
Amount attributable to noncontrolling interests	12.0	(8.3)	(44.6)
Ending balance	(1,545.3)	(1,913.3)	(2,072.4)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(597.2)	(641.8)	(593.8)
Other comprehensive income (loss) before reclassifications	32.0	(8.9)	(112.2)
Amounts reclassified from AOCL	55.9	53.8	64.8
Total Other Comprehensive Income (Loss)	87.9	44.9	(47.4)
Amount attributable to noncontrolling interests	0.3	0.3	0.6
Ending balance	$ (509.6)	$ (597.2)	$ (641.8)