Supplemental Information (NEOM Green Hydrogen Project) (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2022	Sep. 30, 2021
Variable Interest Entity [Line Items]
Cash and cash items	$ 2,957.4	$ 4,468.9
Other receivables and current assets	590.4	550.9
Plant and equipment, at cost	28,349.1	27,488.8
Long-term debt	6,348.0	6,875.7
Noncontrolling Interests	$ 571.8	$ 548.3
Variable Interest Entity, Primary Beneficiary | NEOM Green Hydrogen Company
Variable Interest Entity [Line Items]
Variable Interest Entity, Ownership interest by Air Products (percent)	33.00%
Cash and cash items	$ 258.0
Other receivables and current assets	32.0
Plant and equipment, at cost	144.0
Long-term debt	270.0
Noncontrolling Interests	$ 29.0