Discontinued Operations (Schedule of Operating Results) (Details) - USD ($) $ in Millions		3 Months Ended							9 Months Ended
		Jun. 30, 2017		Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016		Mar. 31, 2016	Jun. 30, 2017		Jun. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations, net of tax		$ (2.3)				$ 98.4			$ 1,871.5		$ (567.0)
Net Income Attributable to Noncontrolling Interests of Discontinued Operations		0.0				1.9			0.0		6.0
Net Income (Loss) From Discontinued Operations, net of tax		(2.3)				96.5			1,871.5		(573.0)
Performance Materials Division [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal, net of tax				$ 1,833.0
Energy-from-Waste [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss on disposal, net of tax					$ (47.1)			$ (846.6)
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales						519.9			254.8		1,503.2
Cost of sales		2.3	[1]			336.7			194.2		947.8
Selling and administrative		0.3	[1]			44.2			23.0		122.7
Research and development						15.6			5.1		45.8
Other income (expense), net		(0.8)	[1]			6.8			(0.6)		1.8
Operating Income (Loss)						130.2			31.9		388.7
Equity affiliates’ income						0.5			0.3		1.1
Income (Loss) Before Taxes		(3.4)	[1]			130.7	[2]		32.2		389.8	[2]
Income tax provision		(1.1)	[1]			32.3			(53.9)	[3]	110.2
Income (Loss) From Operations of Discontinued Operations, net of tax									86.1		279.6
Gain (loss) on disposal, net of tax									1,785.4
Loss on disposal, net of tax											(846.6)
Income (loss) from discontinued operations, net of tax		$ (2.3)	[1]			98.4			1,871.5		(567.0)
Net Income Attributable to Noncontrolling Interests of Discontinued Operations						1.9					6.0
Net Income (Loss) From Discontinued Operations, net of tax						96.5					(573.0)
Income before taxes from operations of discontinued operations						128.3					382.4
Discontinued Operations [Member] | Electronic Materials Division [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales						240.0					713.3
Cost of sales						130.9					385.8
Selling and administrative						22.8					61.2
Research and development						10.6					30.2
Other income (expense), net						(0.8)					4.2
Operating Income (Loss)						74.9					240.3
Equity affiliates’ income						0.0					0.2
Income (Loss) Before Taxes						74.9					240.5
Income tax provision						16.8					58.4
Income (Loss) From Operations of Discontinued Operations, net of tax											182.1
Loss on disposal, net of tax											0.0
Income (loss) from discontinued operations, net of tax						58.1					182.1
Net Income Attributable to Noncontrolling Interests of Discontinued Operations						1.9					6.0
Net Income (Loss) From Discontinued Operations, net of tax						56.2					176.1
Discontinued Operations [Member] | Performance Materials Division [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales						279.9			254.8		789.9
Cost of sales						188.2			182.3		539.1
Selling and administrative						20.7			22.5		59.2
Research and development						4.9			5.1		14.8
Other income (expense), net						(0.6)			0.3		3.1
Operating Income (Loss)						65.5			45.2		179.9
Equity affiliates’ income						0.5			0.3		0.9
Income (Loss) Before Taxes						66.0			45.5		180.8
Income tax provision						16.8			(50.8)	[3]	53.7
Income (Loss) From Operations of Discontinued Operations, net of tax									96.3		127.1
Gain (loss) on disposal, net of tax	[4]								1,832.5
Loss on disposal, net of tax											0.0
Income (loss) from discontinued operations, net of tax						49.2			1,928.8		127.1
Net Income Attributable to Noncontrolling Interests of Discontinued Operations						0.0					0.0
Net Income (Loss) From Discontinued Operations, net of tax						49.2					127.1
Discontinued operations, allowance adjustment effect on income tax provision					$ 66.0
Gross expense related to income tax reserves for uncertain tax positions included in gain									26.1
Net expense related to income tax reserves for uncertain tax positions included in gain									19.1
Discontinued Operations [Member] | Energy-from-Waste [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales						0.0			0.0		0.0
Cost of sales						17.6			11.9		22.9
Selling and administrative						0.7			0.5		2.3
Research and development						0.1			0.0		0.8
Other income (expense), net						8.2			(0.9)		(5.5)
Operating Income (Loss)						(10.2)	[5]		(13.3)	[6]	(31.5)	[5]
Equity affiliates’ income						0.0			0.0		0.0
Income (Loss) Before Taxes						(10.2)	[5]		(13.3)	[6]	(31.5)	[5]
Income tax provision						(1.3)			(3.1)		(1.9)
Income (Loss) From Operations of Discontinued Operations, net of tax									(10.2)	[6]	(29.6)	[5]
Gain (loss) on disposal, net of tax									(47.1)
Loss on disposal, net of tax											(846.6)
Income (loss) from discontinued operations, net of tax						(8.9)	[5]		$ (57.3)		(876.2)	[5]
Net Income Attributable to Noncontrolling Interests of Discontinued Operations						0.0					0.0
Net Income (Loss) From Discontinued Operations, net of tax	[5]					$ (8.9)					$ (876.2)

[1] Activity primarily relates to EfW.

[2] For the three and nine months ended 30 June 2016, income before taxes from operations of discontinued operations attributable to Air Products was $128.3 and $382.4, respectively.

[3] As a result of the expected gain on sale of PMD, we released valuation allowances related to capital loss and net operating loss carryforwards during the first quarter of 2017 that favorably impacted our income tax provision within discontinued operations by approximately $66.

[4] After-tax gain on sale of $1,832.5 includes expense for income tax reserves for uncertain tax positions of $26.1 gross ($19.1 net) in various jurisdictions.

[5] The loss from operations of discontinued operations for EfW primarily relates to project suspension costs, land lease obligations, and administrative costs.

[6] The loss from operations of discontinued operations for EfW primarily relates to land lease obligations, administrative costs, and costs incurred for ongoing project exit activities.