Variable Interest Entities - NGHC Joint Venture Project Financing (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	May 31, 2023	Dec. 31, 2024	Sep. 30, 2024
Variable Interest Entity [Line Items]
Short-term borrowings		$ 68.2	$ 83.5
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Voting interest in joint venture		33.30%
Value of engineering, procurement, and construction agreement	$ 6,700.0
Short-term borrowings		$ 60.4	51.6
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company | De-designated interest rate swap
Variable Interest Entity [Line Items]
Unrealized gain on de-designated cash flow hedging instruments, before tax		38.8
Unrealized gain on de-designated cash flow hedging instruments attributable to Air Products, after tax		10.3
Unrealized Gain on De-Designated Cash Flow Hedging Instruments, Attributable To Noncontrolling Interest, Before Tax		25.2
Variable Interest Entity, Primary Beneficiary | Nonrecourse | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Long-term debt, principal amount		3,800.0	3,300.0
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Project Financing, Primary | Nonrecourse | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Project financing maximum borrowing capacity		$ 6,100.0
Amount of expected debt funding (percent)		73.00%
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Project Financing, Working Capital | Nonrecourse | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Project financing maximum borrowing capacity		$ 500.0
Variable Interest Entity, Primary Beneficiary | Saudi Riyal Loan Facility Variable-Rate 5.70% | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Short-term borrowings		$ 60.4	$ 51.6
Interest rate, variable percentage		5.70%