Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income/expense, net		$ (12.3)	$ (8.6)
Interest expense		18.7	37.3
Other non-operating income (expense), net		(9.1)	(18.5)
Net Income Attributable to Air Products		(475.6)	(347.5)
Reclassification out of Accumulated Other Comprehensive Income | (Gain) Loss on Cash Flow Hedges, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales/Cost of sales		0.0
Other income/expense, net		0.0
Interest expense		0.7
Other non-operating income (expense), net	[1]	(4.3)
Net Income Attributable to Air Products		(3.6)
Reclassification out of Accumulated Other Comprehensive Income | (Gain) Loss on Cash Flow Hedges, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Sales/Cost of sales			0.5
Other income/expense, net			(7.4)
Interest expense			3.8
Other non-operating income (expense), net			0.0
Net Income Attributable to Air Products			(3.1)
Reclassification out of Accumulated Other Comprehensive Income | Pension and Postretirement Benefits, net of tax
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Income Attributable to Air Products	[2]	$ 19.7	$ 15.2

[1] The fiscal year 2020 impact includes amortization of the excluded component and the effective portion of the related hedges.

[2] The components of net periodic benefit cost reclassified out of AOCL include items such as prior service cost amortization, actuarial loss amortization, and settlements and are included in “Other non-operating income (expense), net” on the consolidated income statements. Refer to Note 10, Retirement Benefits, for additional information.