Variable Interest Entities - By Balance Sheet Items (Details) - USD ($) $ in Millions		Mar. 31, 2024	Sep. 30, 2023
Variable Interest Entity [Line Items]
Cash and cash items		$ 2,535.0	$ 1,617.0
Trade receivables, net		1,715.8	1,700.4
Prepaid expenses		263.3	177.0
Other receivables and current assets		719.2	722.1
Total Current Assets		6,057.3	5,200.5
Plant and equipment, net		20,000.5	17,472.1
Operating lease right-of-use assets, net		998.8	974.0
Other noncurrent assets		1,236.4	1,229.9
Total noncurrent assets		29,864.4	26,802.0
Total assets	[1]	35,921.7	32,002.5
Payables and accrued liabilities		2,783.0	2,890.1
Accrued income taxes		156.2	131.2
Short-term borrowings		184.3	259.5
Total Current Liabilities		4,061.0	3,895.8
Noncurrent operating lease liabilities		652.1	631.1
Other noncurrent liabilities		1,092.5	1,118.0
Deferred income taxes		1,281.3	1,266.0
Total noncurrent liabilities		15,525.8	12,446.4
Total Liabilities	[1]	19,586.8	16,342.2
Accumulated other comprehensive income		(2,275.9)	(2,449.4)
Noncontrolling interests	[1]	1,421.5	1,347.4
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Cash and cash items		174.9	78.2
Trade receivables, net		4.6	0.0
Prepaid expenses		30.6	21.4
Other receivables and current assets		203.1	181.6
Total Current Assets		413.2	281.2
Plant and equipment, net		2,358.5	1,396.1
Operating lease right-of-use assets, net		228.8	228.9
Other noncurrent assets		178.2	350.6
Total noncurrent assets		2,765.5	1,975.6
Total assets		3,178.7	2,256.8
Payables and accrued liabilities		174.3	141.0
Accrued income taxes		2.7	0.6
Short-term borrowings		162.7	0.0
Total Current Liabilities		339.7	141.6
Long-term debt		2,114.3	1,274.4
Noncurrent operating lease liabilities		19.5	18.9
Other noncurrent liabilities		11.8	2.1
Deferred income taxes		13.7	24.1
Total noncurrent liabilities		2,159.3	1,319.5
Total Liabilities		2,499.0	1,461.1
Accumulated other comprehensive income		46.1	77.7
Noncontrolling interests		$ 748.1	$ 723.6

[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 $3,178.7 and $2,256.8 as of 31 March 2024 and 30 September 2023, 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 $2,499.0 and $1,461.1 as of 31 March 2024 and 30 September 2023, respectively. Refer to Note 3, Variable Interest Entities, for additional information regarding the NEOM Green Hydrogen Company joint venture.