Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Jun. 30, 2026		Jun. 30, 2025		Jun. 30, 2026		Jun. 30, 2025
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		$ 18,149.8		$ 16,779.6		$ 17,349.8		$ 18,673.7
Other comprehensive income before reclassifications		82.9				85.5
Amounts reclassified from AOCL		6.2				58.3
Total Other Comprehensive Income		89.1		531.9		143.8		140.3
Amount attributable to noncontrolling interests		21.7		24.0		46.1		82.4
Ending balance		16,596.4		17,768.0		16,596.4		17,768.0
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(2,057.5)	[1]	(2,477.7)	[1]	(2,087.8)	[2]	(2,027.7)	[2]
Total Other Comprehensive Income		67.4	[1]	507.9	[1]	97.7	[2]	57.9	[2]
Ending balance	[1],[2]	(1,990.1)		$ (1,969.8)		(1,990.1)		$ (1,969.8)
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		87.2				49.3
Other comprehensive income before reclassifications		42.5				77.1
Amounts reclassified from AOCL		(2.7)				30.2
Total Other Comprehensive Income		39.8				107.3
Amount attributable to noncontrolling interests		17.0				46.6
Ending balance		110.0				110.0
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(1,667.6)				(1,640.7)
Other comprehensive income before reclassifications		40.4				8.4
Amounts reclassified from AOCL		0.0				0.0
Total Other Comprehensive Income		40.4				8.4
Amount attributable to noncontrolling interests		4.9				(0.2)
Ending balance		(1,632.1)				(1,632.1)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(477.1)				(496.4)
Other comprehensive income before reclassifications		0.0				0.0
Amounts reclassified from AOCL		8.9				28.1
Total Other Comprehensive Income		8.9				28.1
Amount attributable to noncontrolling interests		(0.2)				(0.3)
Ending balance		$ (468.0)				$ (468.0)

[1] Accumulated other comprehensive loss

[2] (A)Accumulated other comprehensive loss.