Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions		3 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Segment Reporting Information [Line Items]
Sales		$ 2,254.7	$ 2,224.0
Operating income (loss)		561.0	455.0
Depreciation and amortization		289.2	258.0
Equity affiliates' income		58.2	52.9
Total assets		19,651.6		$ 18,942.8
Operating Segments
Segment Reporting Information [Line Items]
Sales	[1]	2,254.7	2,224.0
Operating income (loss)	[2]	561.0	484.0
Depreciation and amortization		289.2	258.0
Equity affiliates' income		58.2	52.9
Total assets		19,651.6		18,942.8
Industrial Gases - Americas | Operating Segments
Segment Reporting Information [Line Items]
Sales	[1]	936.2	989.2
Operating income (loss)	[2]	257.2	219.2
Depreciation and amortization		131.8	125.6
Equity affiliates' income		20.6	22.6
Total assets		5,971.3		5,832.2
Industrial Gases - EMEA | Operating Segments
Segment Reporting Information [Line Items]
Sales	[1]	498.7	524.2
Operating income (loss)	[2]	120.5	105.6
Depreciation and amortization		48.4	46.3
Equity affiliates' income		19.3	13.7
Total assets		3,509.3		3,250.8
Industrial Gases - Asia | Operating Segments
Segment Reporting Information [Line Items]
Sales	[1]	692.8	626.8
Operating income (loss)	[2]	228.5	201.8
Depreciation and amortization		101.6	79.9
Equity affiliates' income		16.9	16.2
Total assets		6,478.7		6,240.6
Industrial Gases - Global | Operating Segments
Segment Reporting Information [Line Items]
Sales	[1]	92.6	68.2
Operating income (loss)	[2]	3.6	3.9
Depreciation and amortization		2.4	2.1
Equity affiliates' income		1.4	0.4
Total assets		365.0		325.7
Corporate and other | Operating Segments
Segment Reporting Information [Line Items]
Sales	[1]	34.4	15.6
Operating income (loss)	[2]	(48.8)	(46.5)
Depreciation and amortization		5.0	4.1
Equity affiliates' income		0.0	$ 0.0
Total assets		$ 3,327.3		$ 3,293.5

[1] The sales information noted above relates to external customers only. All intersegment sales are eliminated in consolidation. Intersegment sales are generally transacted at market pricing. We generally do not have intersegment sales from our regional industrial gases businesses. Equipment manufactured for our regional industrial gases segments are generally transferred at cost and are not reflect as an intersegment sale.

[2] Refer to the Reconciliation to Consolidated Results section below.