Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
		Mar. 31, 2026		Mar. 31, 2025		Mar. 31, 2026		Mar. 31, 2025
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		$ 17,837.1		$ 18,738.7		$ 17,349.8		$ 18,673.7
Other comprehensive loss before reclassifications		(106.4)				2.6
Amounts reclassified from AOCL		26.2				52.1
Total Other Comprehensive Income (Loss)		(80.2)		63.8		54.7		(391.6)
Amount attributable to noncontrolling interests		0.2		(44.7)		24.4		58.4
Ending balance		18,149.8		16,779.6		18,149.8		16,779.6
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		74.1				49.3
Other comprehensive loss before reclassifications		(0.9)				34.6
Amounts reclassified from AOCL		16.3				32.9
Total Other Comprehensive Income (Loss)		15.4				67.5
Amount attributable to noncontrolling interests		2.3				29.6
Ending balance		87.2				87.2
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(1,564.2)				(1,640.7)
Other comprehensive loss before reclassifications		(105.5)				(32.0)
Amounts reclassified from AOCL		0.0				0.0
Total Other Comprehensive Income (Loss)		(105.5)				(32.0)
Amount attributable to noncontrolling interests		(2.1)				(5.1)
Ending balance		(1,667.6)				(1,667.6)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(487.0)				(496.4)
Other comprehensive loss before reclassifications		0.0				0.0
Amounts reclassified from AOCL		9.9				19.2
Total Other Comprehensive Income (Loss)		9.9				19.2
Amount attributable to noncontrolling interests		0.0				(0.1)
Ending balance		(477.1)				(477.1)
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(1,977.1)	[1]	(2,586.2)	[1]	(2,087.8)	[2]	(2,027.7)	[2]
Total Other Comprehensive Income (Loss)		(80.4)	[1]	108.5	[1]	30.3	[2]	(450.0)	[2]
Ending balance	[1],[2]	$ (2,057.5)		$ (2,477.7)		$ (2,057.5)		$ (2,477.7)

[1] Accumulated other comprehensive loss

[2] (A)Accumulated other comprehensive loss.