Consolidated Income Statements - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2017		Sep. 30, 2016		Sep. 30, 2015
Income Statement [Abstract]
Sales	$ 8,187.6		$ 7,503.7		$ 7,824.3
Cost of sales	5,753.4		5,176.6		5,598.2
Selling and administrative	715.6		685.0		773.0
Research and development	57.8		71.6		76.4
Business separation costs	30.2	[1]	50.6	[1]	7.5
Business restructuring and cost reduction actions	151.4	[2]	34.5	[2]	180.1
Pension settlement loss	10.5	[3]	5.1	[3]	19.3
Goodwill and intangible asset impairment charge	162.1	[4]	0.0		0.0
Gain on previously held equity interest	0.0		0.0		17.9
Other income (expense), net	121.0		49.4		45.5
Operating Income	1,427.6	[5]	1,529.7	[5]	1,233.2
Equity affiliates' income	80.1	[6]	147.0		152.3
Interest expense	120.6		115.2		102.8
Other non-operating income (expense), net	29.0		0.0		0.0
Loss on extinguishment of debt	0.0		6.9	[7]	16.6
Income From Continuing Operations Before Taxes	1,416.1		1,554.6		1,266.1
Income tax provision	260.9	[8]	432.6	[9]	300.2
Income From Continuing Operations	1,155.2		1,122.0		965.9
Income (Loss) From Discontinued Operations, net of tax	1,866.0		(460.5)		351.7
Net Income	3,021.2		661.5		1,317.6
Net Income Attributable to Noncontrolling Interests of Continuing Operations	20.8		22.5		32.6
Net Income Attributable to Noncontrolling Interests of Discontinued Operations	0.0		7.9		7.1
Net Income Attributable to Air Products	3,000.4		631.1		1,277.9
Net Income Attributable to Air Products
Income from continuing operations	1,134.4		1,099.5		933.3
Income (Loss) from discontinued operations	1,866.0	[10]	(468.4)		344.6
Net Income Attributable to Air Products	$ 3,000.4		$ 631.1		$ 1,277.9
Basic Earnings Per Common Share Attributable to Air Products
Income from continuing operations (in dollars per share)	$ 5.20		$ 5.08		$ 4.34
Income (Loss) from discontinued operations (in dollars per share)	8.56		(2.16)		1.61
Net Income Attributable to Air Products (in dollars per share)	13.76		2.92		5.95
Diluted Earnings Per Common Share Attributable to Air Products
Income from continuing operations (in dollars per share)	5.16		5.04		4.29
Income (Loss) from discontinued operations (in dollars per share)	8.49		(2.15)		1.59
Net Income Attributable to Air Products (in dollars per share)	$ 13.65		$ 2.89		$ 5.88
Weighted Average Common Shares - Basic (in millions)	218.0		216.4		214.9
Weighted Average Common Shares - Diluted (in millions)	219.8		218.3		217.3

[1] For additional information, see Note 4, Materials Technologies Separation.

[2] For additional information, see Note 5, Business Restructuring and Cost Reduction Actions.

[3] For additional information, see Note 16, Retirement Benefits.

[4] For additional information, see Note 10, Goodwill, and Note 11, Intangible Assets.

[5] Changes in estimates on projects accounted for under the percentage of completion method favorably impacted income by approximately $27 in fiscal year 2017 and $20 in fiscal year 2016, primarily during the fourth quarter. For additional information, see Note 1, Major Accounting Policies (Revenue Recognition).

[6] Includes the impact of an other-than-temporary impairment of an investment in an equity affiliate. For additional information, see Note 8, Summarized Financial Information of Equity Affiliates.

[7] For additional information, see Note 15, Debt.

[8] Includes the impact of a tax election benefit related to a non-U.S. subsidiary. For additional information, see Note 22, Income Taxes.

[9] Includes income tax expense for tax costs associated with business separation. For additional information, see Note 4, Materials Technologies Separation.

[10] Includes the after-tax gain on the sale of PMD. For additional information, see Note 3, Discontinued Operations.