Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 14,690.2	$ 14,510.7	$ 13,702.4	$ 14,088.0
Other comprehensive income (loss) before reclassifications	(135.0)		538.7
Amounts reclassified from AOCL	(10.9)		(47.8)
Total Other Comprehensive Income (Loss)	(145.9)	(563.2)	490.9	(544.7)
Amount attributable to noncontrolling interests	(4.4)	(18.2)	9.6	(10.0)
Ending balance	15,370.7	14,215.7	15,370.7	14,215.7
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(26.5)		(71.9)
Other comprehensive income (loss) before reclassifications	40.8		147.2
Amounts reclassified from AOCL	(24.4)		(87.3)
Total Other Comprehensive Income (Loss)	16.4		59.9
Amount attributable to noncontrolling interests	11.4		9.5
Ending balance	(21.5)		(21.5)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,527.9)		(2,072.4)
Other comprehensive income (loss) before reclassifications	(175.8)		384.8
Amounts reclassified from AOCL	0.0		(0.3)
Total Other Comprehensive Income (Loss)	(175.8)		384.5
Amount attributable to noncontrolling interests	(15.9)		(0.1)
Ending balance	(1,687.8)		(1,687.8)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(608.9)		(641.8)
Other comprehensive income (loss) before reclassifications	0.0		6.7
Amounts reclassified from AOCL	13.5		39.8
Total Other Comprehensive Income (Loss)	13.5		46.5
Amount attributable to noncontrolling interests	0.1		0.2
Ending balance	(595.5)		(595.5)
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,163.3)	(1,505.6)	(2,786.1)	(1,515.9)
Total Other Comprehensive Income (Loss)	(141.5)	(545.0)	481.3	(534.7)
Ending balance	$ (2,304.8)	$ (2,050.6)	$ (2,304.8)	$ (2,050.6)