Accumulated Other Comprehensive Loss (Reclassification) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other (income) expense, net										$ (47.3)	$ (52.8)	$ (70.2)
Interest expense										103.5	125.1	141.8
Net Income Attributable to Air Products		$ (344.5)	$ (318.8)	$ (290.0)	$ (324.6)	$ (104.0)	$ (314.0)	$ (283.5)	$ (290.2)	(1,277.9)	(991.7)	(994.2)
Income (Loss) from discontinued operations, net of tax										0.0	(4.6)	10.0
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | (Gain) Loss on Cash Flow Hedges [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Sales/cost of sales										0.6	0.7	1.0
Other (income) expense, net										16.9	(8.7)	(21.5)
Interest expense										3.3	(1.1)	0.3
Net Income Attributable to Air Products										20.8	(9.1)	(20.2)
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Pension and postretirement benefits [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net Income Attributable to Air Products	[1]									97.0	84.7	104.9
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Accumulated Translation Adjustment [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income (Loss) from discontinued operations, net of tax	[2]									$ 0.0	$ 0.0	$ 0.6

[1] The components include items such as prior service cost amortization, actuarial loss amortization, and settlements and are reflected in net periodic benefit cost. Refer to Note 16, Retirement Benefits.

[2] The impact is reflected in Income from Discontinued Operations, net of tax.