Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 15,660.3	$ 13,702.4
Other comprehensive (loss) income before reclassifications	219.5
Amounts reclassified from AOCL	(28.5)
Total Other Comprehensive Income	191.0	580.5
Amount attributable to noncontrolling interests	(138.1)	12.7
Ending balance	16,129.1	14,517.4
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	61.1
Other comprehensive (loss) income before reclassifications	(161.1)
Amounts reclassified from AOCL	(42.2)
Total Other Comprehensive Income	(203.3)
Amount attributable to noncontrolling interests	(154.1)
Ending balance	11.9
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,913.3)
Other comprehensive (loss) income before reclassifications	380.6
Amounts reclassified from AOCL	0.0
Total Other Comprehensive Income	380.6
Amount attributable to noncontrolling interests	16.0
Ending balance	(1,548.7)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(597.2)
Other comprehensive (loss) income before reclassifications	0.0
Amounts reclassified from AOCL	13.7
Total Other Comprehensive Income	13.7
Amount attributable to noncontrolling interests	0.0
Ending balance	(583.5)
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,449.4)	(2,786.1)
Total Other Comprehensive Income	329.1	567.8
Ending balance	$ (2,120.3)	$ (2,218.3)