Variable Interest Entities (By Balance Sheet Items) (Details) - USD ($) $ in Millions		Jun. 30, 2023	Sep. 30, 2022
Variable Interest Entity [Line Items]
Cash and cash items		$ 1,637.7	$ 2,711.0
Trade receivables, net		1,934.2	1,794.4
Prepaid expenses		179.2	156.8
Other receivables and current assets		670.3	515.8
Total current assets		5,354.0	6,282.9
Plant and equipment, net		16,512.8	14,160.5
Operating lease right-of-use assets, net		970.8	694.8
Other noncurrent assets		1,010.7	947.0
Total noncurrent assets		25,575.5	20,909.7
Total Assets	[1]	30,929.5	27,192.6
Payables and accrued liabilities		3,062.2	2,771.6
Accrued income taxes		108.8	135.2
Total current liabilities		3,947.7	3,465.8
Noncurrent operating lease liabilities		635.5	592.1
Other noncurrent liabilities		1,144.6	1,099.1
Deferred income taxes		1,215.8	1,247.4
Total noncurrent liabilities		11,611.1	10,024.4
Total Liabilities	[1]	15,558.8	13,490.2
Accumulated other comprehensive income		(2,304.8)	(2,786.1)
Noncontrolling interests	[1]	1,232.7	558.4
Related Party
Variable Interest Entity [Line Items]
Trade receivables, net		255.0	55.0
Long-term debt		148.7	652.0
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Cash and cash items		87.8	274.7
Trade receivables, net		0.0	1.3
Prepaid expenses		5.0	0.1
Other receivables and current assets		108.5	23.3
Total current assets		201.3	299.4
Plant and equipment, net		1,031.4	218.8
Operating lease right-of-use assets, net		226.8	0.0
Other noncurrent assets		161.7	1.5
Total noncurrent assets		1,419.9	220.3
Total Assets		1,621.2	519.7
Payables and accrued liabilities		474.7	58.1
Accrued income taxes		0.1	0.0
Total current liabilities		474.8	58.1
Noncurrent operating lease liabilities		17.9	0.0
Other noncurrent liabilities		2.6	1.4
Deferred income taxes		1.3	0.0
Total noncurrent liabilities		21.8	448.7
Total Liabilities		496.6	506.8
Accumulated other comprehensive income		4.0	0.0
Noncontrolling interests		605.1	30.0
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company | Related Party
Variable Interest Entity [Line Items]
Long-term debt		$ 0.0	$ 447.3

[1] Includes balances associated with a consolidated variable interest entity ("VIE"), including amounts reflected in "Total Assets" that can only be used to settle obligations of the VIE of $1,621.2 and $519.7 as of 30 June 2023 and 30 September 2022, respectively, as well as liabilities of the VIE reflected within "Total Liabilities" for which creditors do not have recourse to the general credit of Air Products of $496.6 and $506.8 as of 30 June 2023 and 30 September 2022, respectively. Refer to Note 3, Variable Interest Entities, for additional information.