Accumulated Other Comprehensive Loss (Rollforward) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 14,375.6	$ 13,071.9	$ 14,088.0	$ 12,443.1
Other comprehensive loss before reclassifications	(98.2)		(58.1)
Amounts reclassified from AOCL	41.9		76.6
Total Other Comprehensive Income (Loss)	(56.3)	(95.5)	18.5	351.0
Amount attributable to noncontrolling interests	(3.0)	15.6	8.2	35.3
Ending balance	14,510.7	13,134.8	14,510.7	13,134.8
Derivatives qualifying as hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(17.5)		(28.3)
Other comprehensive loss before reclassifications	(39.4)		(39.9)
Amounts reclassified from AOCL	26.0		44.7
Total Other Comprehensive Income (Loss)	(13.4)		4.8
Amount attributable to noncontrolling interests	1.1		8.5
Ending balance	(32.0)		(32.0)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(857.0)		(893.8)
Other comprehensive loss before reclassifications	(58.8)		(18.2)
Amounts reclassified from AOCL	0.0		0.0
Total Other Comprehensive Income (Loss)	(58.8)		(18.2)
Amount attributable to noncontrolling interests	(4.2)		(0.4)
Ending balance	(911.6)		(911.6)
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(577.8)		(593.8)
Other comprehensive loss before reclassifications	0.0		0.0
Amounts reclassified from AOCL	15.9		31.9
Total Other Comprehensive Income (Loss)	15.9		31.9
Amount attributable to noncontrolling interests	0.1		0.1
Ending balance	(562.0)		(562.0)
AOCL attributable to Air Products
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(1,452.3)	(1,713.3)	(1,515.9)	(2,140.1)
Total Other Comprehensive Income (Loss)	(53.3)	(111.1)	10.3	315.7
Ending balance	$ (1,505.6)	$ (1,824.4)	$ (1,505.6)	$ (1,824.4)