Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014
Segment Reporting Information [Line Items]
Sales	$ 2,470.2	$ 2,634.6	$ 7,445.5	$ 7,762.0
Operating income (loss)	422.5	413.8	1,226.9	1,184.1
Depreciation and amortization			701.8	702.3
Equity affiliates' income (loss)	42.4	43.1	118.5	111.7
Total assets	17,671.5		17,671.5		$ 17,779.1
Segment Total [Member]
Segment Reporting Information [Line Items]
Sales	2,470.2	2,634.6	7,445.5	7,762.0
Operating income (loss)	482.3	413.8	1,369.2	1,184.1
Depreciation and amortization	233.0	239.0	701.8	702.3
Equity affiliates' income (loss)	42.4	43.1	118.5	111.7
Total assets	17,671.5		17,671.5		17,779.1
Industrial Gases - Americas [Member]
Segment Reporting Information [Line Items]
Sales	898.2	1,064.0	2,791.6	3,040.8
Operating income (loss)	206.5	188.9	599.7	543.0
Depreciation and amortization	103.9	105.6	310.8	309.0
Equity affiliates' income (loss)	17.3	14.7	49.6	44.9
Total assets	6,092.4		6,092.4		6,240.7
Industrial Gases - EMEA [Member]
Segment Reporting Information [Line Items]
Sales	455.2	537.4	1,404.8	1,630.0
Operating income (loss)	87.6	85.7	239.9	258.4
Depreciation and amortization	47.0	54.9	145.7	164.8
Equity affiliates' income (loss)	12.1	13.5	30.4	32.5
Total assets	3,268.4		3,268.4		3,521.0
Industrial Gases - Asia [Member]
Segment Reporting Information [Line Items]
Sales	417.6	366.2	1,209.3	1,127.2
Operating income (loss)	100.9	83.8	276.1	237.7
Depreciation and amortization	51.9	50.0	151.8	144.5
Equity affiliates' income (loss)	12.7	13.4	36.7	30.6
Total assets	4,207.1		4,207.1		4,045.6
Industrial Gases - Global [Member]
Segment Reporting Information [Line Items]
Sales	71.3	70.8	197.4	206.4
Operating income (loss)	(24.1)	(14.4)	(49.9)	(39.3)
Depreciation and amortization	4.2	1.7	14.0	5.0
Equity affiliates' income (loss)	0.0	0.7	0.2	1.7
Total assets	291.2		291.2		389.4
Materials Technologies [Member]
Segment Reporting Information [Line Items]
Sales	539.8	524.7	1,597.1	1,503.8
Operating income (loss)	131.5	96.6	360.3	254.7
Depreciation and amortization	22.7	24.5	70.0	71.7
Equity affiliates' income (loss)	0.3	0.8	1.6	2.0
Total assets	1,826.8		1,826.8		1,835.7
Energy-from-Waste [Member]
Segment Reporting Information [Line Items]
Sales	0.0	0.0	0.0	0.0
Operating income (loss)	(2.5)	(3.2)	(7.8)	(9.6)
Depreciation and amortization	0.0	0.0	0.0	0.0
Equity affiliates' income (loss)	0.0	0.0	0.0	0.0
Total assets	846.0		846.0		591.9
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Sales	88.1	71.5	245.3	253.8
Operating income (loss)	(17.6)	(23.6)	(49.1)	(60.8)
Depreciation and amortization	3.3	2.3	9.5	7.3
Equity affiliates' income (loss)	0.0	$ 0.0	0.0	$ 0.0
Total assets	$ 1,139.6		$ 1,139.6		$ 1,154.8