Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Segment Reporting Information [Line Items]
Sales	$ 2,604.7	$ 2,065.2	$ 7,481.9	$ 6,536.2
Operating income (loss)	577.1	539.2	1,664.7	1,677.4
Depreciation and amortization			988.7	874.5
Equity affiliates' income	63.2	51.2	202.3	197.6
Total assets	26,252.1		26,252.1		$ 25,168.5
Operating Segments
Segment Reporting Information [Line Items]
Sales	2,604.7	2,065.2	7,481.9	6,536.2
Operating income (loss)	577.1	539.2	1,651.1	1,643.6
Depreciation and amortization	335.7	290.6	988.7	874.5
Equity affiliates' income	63.2	51.2	202.3	163.8
Total assets	26,252.1		26,252.1		25,168.5
Industrial Gases - Americas | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,063.3	849.9	3,052.4	2,718.5
Operating income (loss)	286.0	248.3	775.2	773.5
Depreciation and amortization	154.2	142.8	459.3	410.1
Equity affiliates' income	24.6	19.9	79.2	62.1
Total assets	7,026.5		7,026.5		6,610.1
Industrial Gases - EMEA | Operating Segments
Segment Reporting Information [Line Items]
Sales	623.3	429.7	1,770.9	1,421.1
Operating income (loss)	140.1	105.1	421.2	350.2
Depreciation and amortization	58.7	47.3	171.7	143.3
Equity affiliates' income	13.5	17.4	58.8	50.2
Total assets	4,288.1		4,288.1		3,917.0
Industrial Gases - Asia | Operating Segments
Segment Reporting Information [Line Items]
Sales	751.8	651.9	2,166.8	2,002.8
Operating income (loss)	219.1	221.9	632.4	659.5
Depreciation and amortization	113.8	92.9	331.4	298.6
Equity affiliates' income	23.5	11.7	58.9	42.4
Total assets	7,503.5		7,503.5		6,842.9
Industrial Gases - Global | Operating Segments
Segment Reporting Information [Line Items]
Sales	99.1	77.6	301.5	249.5
Operating income (loss)	(33.6)	(13.4)	(64.3)	(29.6)
Depreciation and amortization	2.9	2.3	8.1	7.1
Equity affiliates' income	1.6	2.2	5.4	9.1
Total assets	500.4		500.4		397.8
Corporate and other | Operating Segments
Segment Reporting Information [Line Items]
Sales	67.2	56.1	190.3	144.3
Operating income (loss)	(34.5)	(22.7)	(113.4)	(110.0)
Depreciation and amortization	6.1	5.3	18.2	15.4
Equity affiliates' income	0.0	$ 0.0	0.0	$ 0.0
Total assets	$ 6,933.6		$ 6,933.6		$ 7,400.7