Consolidated Income Statements (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Sales	$ 2,155.7	$ 1,980.1	$ 4,372.3	$ 3,862.6
Cost of sales	1,506.5	1,403.8	3,078.3	2,720.5
Selling and administrative	194.6	177.6	386.2	342.3
Research and development	14.5	14.8	29.1	29.8
Business separation costs	0.0	0.0	0.0	32.5
Cost reduction and asset actions	0.0	10.3	0.0	60.3
Other income (expense), net	15.3	22.0	37.4	46.7
Operating Income	455.4	395.6	916.1	723.9
Equity affiliates' income	43.7	34.2	57.5	72.2
Interest expense	30.4	30.5	60.2	60.0
Other non-operating income (expense), net	11.1	5.3	20.9	5.1
Income From Continuing Operations Before Taxes	479.8	404.6	934.3	741.2
Income tax provision	56.2	94.5	348.0	172.9
Income From Continuing Operations	423.6	310.1	586.3	568.3
Income (Loss) From Discontinued Operations, net of tax	0.0	1,825.6	(1.0)	1,873.8
Net Income	423.6	2,135.7	585.3	2,442.1
Net Income Attributable to Noncontrolling Interests of Continuing Operations	7.2	5.7	14.3	12.3
Net Income Attributable to Air Products	416.4	2,130.0	571.0	2,429.8
Net Income Attributable to Air Products
Income from continuing operations	416.4	304.4	572.0	556.0
Income (Loss) from discontinued operations	0.0	1,825.6	(1.0)	1,873.8
Net Income Attributable to Air Products	$ 416.4	$ 2,130.0	$ 571.0	$ 2,429.8
Basic Earnings Per Common Share Attributable to Air Products
Income from continuing operations, basic (in dollars per share)	$ 1.90	$ 1.40	$ 2.61	$ 2.55
Income (Loss) from discontinued operations, basic (in dollars per share)	0	8.38	0	8.61
Net Income (Loss) Attributable to Air Products (in dollars per share)	1.90	9.78	2.61	11.16
Diluted Earnings Per Common Share Attributable to Air Products
Income from continuing operations, diluted (in dollars per share)	1.89	1.39	2.59	2.53
Income (Loss) from discontinued operations, diluted (in dollars per share)	0	8.31	0	8.53
Net Income (Loss) Attributable to Air Products (in dollars per share)	$ 1.89	$ 9.70	$ 2.59	$ 11.06
Weighted Average Common Shares - Basic (in millions)	219.4	217.9	219.2	217.8
Weighted Average Common Shares - Diluted (in millions)	220.8	219.7	220.7	219.6
Dividends Declared Per Common Share - Cash (in dollars per share)	$ 1.10	$ 0.95	$ 2.05	$ 1.81