Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Oct. 01, 2018	Sep. 30, 2018
Segment Reporting Information [Line Items]
Sales	$ 2,224.0	$ 2,259.0	$ 6,635.7	$ 6,631.3
Operating income (loss)	569.7	515.8	1,541.2	1,431.9
Depreciation and amortization			789.2	713.5
Equity affiliates' income	56.4	58.1	155.5	115.6
Total assets	19,531.9		19,531.9		$ 19,204.5	$ 19,178.3
Operating Segments
Segment Reporting Information [Line Items]
Sales	2,224.0	2,259.0	6,635.7	6,631.3
Operating income (loss)	566.1	515.8	1,566.6	1,431.9
Depreciation and amortization	269.1	245.6	789.2	713.5
Equity affiliates' income	56.4	58.1	155.5	148.1
Total assets	19,531.9		19,531.9			19,178.3
Industrial Gases - Americas \| Operating Segments
Segment Reporting Information [Line Items]
Sales	955.3	948.7	2,936.2	2,771.7
Operating income (loss)	262.2	237.1	737.0	676.6
Depreciation and amortization	126.3	120.5	376.8	360.6
Equity affiliates' income	21.7	24.1	62.1	59.6
Total assets	5,896.6		5,896.6			5,904.0
Industrial Gases - EMEA \| Operating Segments
Segment Reporting Information [Line Items]
Sales	494.6	561.1	1,513.2	1,638.6
Operating income (loss)	123.4	118.8	351.5	340.0
Depreciation and amortization	47.8	49.8	140.4	149.6
Equity affiliates' income	18.8	17.5	45.8	41.7
Total assets	3,399.7		3,399.7			3,280.4
Industrial Gases - Asia \| Operating Segments
Segment Reporting Information [Line Items]
Sales	679.4	623.8	1,931.6	1,825.0
Operating income (loss)	231.4	185.5	632.9	509.7
Depreciation and amortization	87.9	69.5	252.7	188.9
Equity affiliates' income	14.9	15.1	44.9	44.7
Total assets	6,357.6		6,357.6			5,899.5
Industrial Gases - Global \| Operating Segments
Segment Reporting Information [Line Items]
Sales	57.9	101.1	179.9	335.8
Operating income (loss)	(9.6)	19.8	(17.9)	41.4
Depreciation and amortization	2.2	2.3	6.3	5.8
Equity affiliates' income	1.0	1.4	2.7	2.1
Total assets	284.3		284.3			240.1
Corporate and other \| Operating Segments
Segment Reporting Information [Line Items]
Sales	36.8	24.3	74.8	60.2
Operating income (loss)	(41.3)	(45.4)	(136.9)	(135.8)
Depreciation and amortization	4.9	3.5	13.0	8.6
Equity affiliates' income	0.0	$ 0.0	0.0	$ 0.0
Total assets	$ 3,593.7		$ 3,593.7			$ 3,854.3

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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