Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 16,334.9	$ 14,690.2	$ 15,660.3	$ 13,702.4
Other comprehensive income (loss) before reclassifications	(126.7)		(48.7)
Amounts reclassified from AOCL	29.3		49.2
Net current period other comprehensive income (loss)	(97.4)	(145.9)	0.5	490.9
Amount attributable to noncontrolling interests	17.8	(4.4)	(57.8)	9.6
Ending balance	16,687.0	15,370.7	16,687.0	15,370.7
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	53.4		61.1
Other comprehensive income (loss) before reclassifications	13.5		(65.3)
Amounts reclassified from AOCL	15.5		8.1
Net current period other comprehensive income (loss)	29.0		(57.2)
Amount attributable to noncontrolling interests	21.5		(57.0)
Ending balance	60.9		60.9
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,759.3)		(1,913.3)
Other comprehensive income (loss) before reclassifications	(140.2)		16.6
Amounts reclassified from AOCL	0.0		0.0
Net current period other comprehensive income (loss)	(140.2)		16.6
Amount attributable to noncontrolling interests	(3.8)		(1.0)
Ending balance	(1,895.7)		(1,895.7)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(570.0)		(597.2)
Other comprehensive income (loss) before reclassifications	0.0		0.0
Amounts reclassified from AOCL	13.8		41.1
Net current period other comprehensive income (loss)	13.8		41.1
Amount attributable to noncontrolling interests	0.1		0.2
Ending balance	(556.3)		(556.3)
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,275.9)	(2,163.3)	(2,449.4)	(2,786.1)
Net current period other comprehensive income (loss)	(115.2)	(141.5)	58.3	481.3
Ending balance	$ (2,391.1)	$ (2,304.8)	$ (2,391.1)	$ (2,304.8)