Business and Asset Actions - Summary of Charges for Business and Asset Actions (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2026	Jun. 30, 2025
Restructuring Cost and Reserve [Line Items]
Charges recorded to operating income/loss	$ 2,907.4	$ 24.1		$ 2,929.4	$ 2,952.0
Project exit-related non-operating charges	0.0	0.0		6.3	6.8
Charges recorded to income/loss from continuing operations before taxes	2,907.4	24.1		2,935.7	2,958.8
Income tax benefit	695.4	8.7		698.5	649.3
Amounts attributable to noncontrolling interests	0.0	0.0		0.6	3.5
Charges attributable to Air Products, after-tax	2,212.0	15.4		2,236.6	2,306.0
Project Exit Costs
Restructuring Cost and Reserve [Line Items]
Charges recorded to operating income/loss	2,907.4	24.1		2,929.4	2,885.9
Global Cost Reduction Plan
Restructuring Cost and Reserve [Line Items]
Charges recorded to operating income/loss	$ 0.0	$ 0.0	$ 66.1	$ 0.0	$ 66.1