Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016
Segment Reporting Information [Line Items]
Sales	$ 2,121.9	$ 1,914.5	$ 5,984.5	$ 5,558.2
Operating income (loss)	252.6	394.6	971.9	1,138.7
Depreciation and amortization			634.8	642.1
Equity affiliates' income (loss)	(36.9)	42.1	35.3	107.7
Total assets	17,853.8		17,853.8		$ 18,028.6
Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	2,121.9	1,914.5	5,984.5	5,558.2
Operating income (loss)	462.9	418.3	1,276.8	1,194.5
Depreciation and amortization	216.9	213.5	634.8	642.1
Equity affiliates' income (loss)	42.6	42.1	114.8	107.7
Total assets	17,844.0		17,844.0		16,060.1
Industrial Gases - Americas [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	930.1	832.3	2,684.1	2,466.7
Operating income (loss)	236.2	234.0	684.5	669.1
Depreciation and amortization	117.0	112.1	344.8	330.9
Equity affiliates' income (loss)	14.1	16.0	41.8	38.2
Total assets	5,765.6		5,765.6		5,896.7
Industrial Gases - EMEA [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	451.7	428.7	1,265.6	1,290.1
Operating income (loss)	94.1	104.0	268.6	286.3
Depreciation and amortization	45.1	45.1	128.9	140.1
Equity affiliates' income (loss)	15.7	11.3	33.5	26.1
Total assets	3,205.4		3,205.4		3,178.6
Industrial Gases - Asia [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	538.3	449.0	1,412.5	1,271.5
Operating income (loss)	149.1	118.7	379.2	341.0
Depreciation and amortization	49.6	49.5	145.6	150.2
Equity affiliates' income (loss)	12.5	14.8	38.9	43.9
Total assets	4,262.6		4,262.6		4,232.7
Industrial Gases - Global [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	187.4	150.8	551.8	341.7
Operating income (loss)	27.9	(13.9)	58.9	(44.0)
Depreciation and amortization	2.3	2.0	6.0	5.9
Equity affiliates' income (loss)	0.3	0.0	0.6	(0.5)
Total assets	283.6		283.6		367.6
Corporate and other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Sales	14.4	53.7	70.5	188.2
Operating income (loss)	(44.4)	(24.5)	(114.4)	(57.9)
Depreciation and amortization	2.9	4.8	9.5	15.0
Equity affiliates' income (loss)	0.0	$ 0.0	0.0	$ 0.0
Total assets	$ 4,326.8		$ 4,326.8		$ 2,384.5