Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Effective tax rate (percent)	21.20%	18.60%	19.90%	17.80%
Business and asset actions	$ 185.6	$ 0.0	$ 185.6	$ 0.0
Business and asset actions attributable to Air Products after tax	153.7
Valuation allowance against deferred tax assets	31.7		31.7
Tax expense (benefit) from tax election	$ (15.9)
Income tax payments, net of refunds			$ 327.0	$ 236.9