Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Oct. 01, 2018	Sep. 30, 2018
Segment Reporting Information [Line Items]
Sales	$ 2,224.0	$ 2,216.6
Operating income (loss)	455.0	460.7
Depreciation and amortization	258.0	227.9
Equity affiliates' income	52.9	13.8
Total assets	19,142.0		$ 19,204.5	$ 19,178.3
Operating Segments
Segment Reporting Information [Line Items]
Sales	2,224.0	2,216.6
Operating income (loss)	484.0	460.7
Depreciation and amortization	258.0	227.9
Equity affiliates' income	52.9	46.3
Total assets	19,142.0			19,178.3
Industrial Gases - Americas | Operating Segments
Segment Reporting Information [Line Items]
Sales	989.2	909.8
Operating income (loss)	219.2	217.2
Depreciation and amortization	125.6	117.8
Equity affiliates' income	22.6	18.6
Total assets	5,859.6			5,904.0
Industrial Gases - EMEA | Operating Segments
Segment Reporting Information [Line Items]
Sales	524.2	515.9
Operating income (loss)	105.6	104.5
Depreciation and amortization	46.3	49.1
Equity affiliates' income	13.7	13.1
Total assets	3,214.6			3,280.4
Industrial Gases - Asia | Operating Segments
Segment Reporting Information [Line Items]
Sales	626.8	643.6
Operating income (loss)	201.8	175.5
Depreciation and amortization	79.9	56.8
Equity affiliates' income	16.2	14.2
Total assets	6,037.0			5,899.5
Industrial Gases - Global | Operating Segments
Segment Reporting Information [Line Items]
Sales	68.2	133.0
Operating income (loss)	3.9	9.5
Depreciation and amortization	2.1	1.6
Equity affiliates' income	0.4	0.4
Total assets	255.4			240.1
Corporate and other | Operating Segments
Segment Reporting Information [Line Items]
Sales	15.6	14.3
Operating income (loss)	(46.5)	(46.0)
Depreciation and amortization	4.1	2.6
Equity affiliates' income	0.0	$ 0.0
Total assets	$ 3,775.4			$ 3,854.3