Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 18,673.7	$ 15,660.3	$ 13,702.4
Other comprehensive income (loss) before reclassifications	(87.9)	254.0	511.4
Amounts reclassified from AOCL	92.9	20.7	9.6
Total Other Comprehensive Income	5.0	274.7	521.0
Amount attributable to noncontrolling interests	65.1	(147.0)	184.3
Ending balance	17,349.8	18,673.7	15,660.3
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,027.7)	(2,449.4)	(2,786.1)
Total Other Comprehensive Income	(60.1)	421.7	336.7
Ending balance	(2,087.8)	(2,027.7)	(2,449.4)
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	27.2	61.1	(71.9)
Other comprehensive income (loss) before reclassifications	40.0	(159.5)	369.2
Amounts reclassified from AOCL	41.2	(33.7)	(43.9)
Total Other Comprehensive Income	81.2	(193.2)	325.3
Amount attributable to noncontrolling interests	59.1	(159.3)	192.3
Ending balance	49.3	27.2	61.1
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,545.3)	(1,913.3)	(2,072.4)
Other comprehensive income (loss) before reclassifications	(95.6)	381.5	151.1
Amounts reclassified from AOCL	5.7	(1.5)	(0.3)
Total Other Comprehensive Income	(89.9)	380.0	150.8
Amount attributable to noncontrolling interests	5.5	12.0	(8.3)
Ending balance	(1,640.7)	(1,545.3)	(1,913.3)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(509.6)	(597.2)	(641.8)
Other comprehensive income (loss) before reclassifications	(32.3)	32.0	(8.9)
Amounts reclassified from AOCL	46.0	55.9	53.8
Total Other Comprehensive Income	13.7	87.9	44.9
Amount attributable to noncontrolling interests	0.5	0.3	0.3
Ending balance	$ (496.4)	$ (509.6)	$ (597.2)