Consolidated Income Statements (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Sales	$ 2,259.0	$ 2,121.9	$ 6,631.3	$ 5,984.5
Cost of sales	1,545.4	1,486.0	4,623.7	4,206.5
Selling and administrative	188.6	184.1	574.8	526.4
Research and development	15.0	14.6	44.1	44.4
Business separation costs	0.0	0.0	0.0	32.5
Cost reduction and asset actions	0.0	42.7	0.0	103.0
Goodwill and intangible asset impairment charge	0.0	162.1	0.0	162.1
Other income (expense), net	5.8	26.3	43.2	73.0
Operating Income	515.8	258.7	1,431.9	982.6
Equity affiliates' income (loss)	58.1	(36.9)	115.6	35.3
Interest expense	34.9	29.8	95.1	89.8
Other non-operating income (expense), net	12.8	3.7	33.7	8.8
Income From Continuing Operations Before Taxes	551.8	195.7	1,486.1	936.9
Income tax provision	107.1	89.3	455.1	262.2
Income From Continuing Operations	444.7	106.4	1,031.0	674.7
Income (Loss) From Discontinued Operations, net of tax	43.2	(2.3)	42.2	1,871.5
Net Income	487.9	104.1	1,073.2	2,546.2
Net Income Attributable to Noncontrolling Interests of Continuing Operations	14.0	2.2	28.3	14.5
Net Income Attributable to Air Products	473.9	101.9	1,044.9	2,531.7
Net Income Attributable to Air Products
Income from continuing operations	430.7	104.2	1,002.7	660.2
Income (Loss) from discontinued operations	43.2	(2.3)	42.2	1,871.5
Net Income Attributable to Air Products	$ 473.9	$ 101.9	$ 1,044.9	$ 2,531.7
Basic Earnings Per Common Share Attributable to Air Products
Income from continuing operations, basic (in dollars per share)	$ 1.96	$ 0.48	$ 4.57	$ 3.03
Income (Loss) from discontinued operations, basic (in dollars per share)	0.20	(0.01)	0.19	8.59
Net Income Attributable to Air Products (in dollars per share)	2.16	0.47	4.76	11.62
Diluted Earnings Per Common Share Attributable to Air Products
Income from continuing operations, diluted (in dollars per share)	1.95	0.47	4.54	3.00
Income (Loss) from discontinued operations, diluted (in dollars per share)	0.20	(0.01)	0.19	8.52
Net Income Attributable to Air Products (in dollars per share)	$ 2.15	$ 0.46	$ 4.73	$ 11.52
Weighted Average Common Shares - Basic (in millions)	219.5	218.1	219.3	217.9
Weighted Average Common Shares - Diluted (in millions)	220.9	219.8	220.7	219.8
Dividends Declared Per Common Share - Cash (in dollars per share)	$ 1.10	$ 0.95	$ 3.15	$ 2.76