Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Tax Disclosure [Abstract]
Effective tax rate (percent)	18.60%	18.60%	19.40%	18.10%
Business and asset actions	$ 59.0	$ 0.0	$ 244.6	$ 0.0
Business and asset actions attributable to Air Products after tax	51.2		204.9
Valuation allowance against deferred tax assets	$ 36.0		36.0
Income tax benefit from a tax election			15.9
Income tax payments, net of refunds			$ 487.6	$ 341.3