Business Segment Information (Schedule of Segment Reporting Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2015
Segment Reporting Information [Line Items]
Sales	$ 2,355.8	$ 2,560.8
Operating income (loss)	493.0	430.0
Depreciation and amortization	232.7	235.5
Equity affiliates' income	33.7	43.1
Total assets	17,260.3		$ 17,334.5
Segment Total [Member]
Segment Reporting Information [Line Items]
Sales	2,355.8	2,560.8
Operating income (loss)	519.3	444.5
Depreciation and amortization	232.7	235.5
Equity affiliates' income	33.7	43.1
Total assets	17,260.3		17,334.5
Industrial Gases - Americas [Member]
Segment Reporting Information [Line Items]
Sales	836.1	1,003.0
Operating income (loss)	211.8	211.2
Depreciation and amortization	108.8	103.6
Equity affiliates' income	14.5	17.2
Total assets	5,674.3		5,774.9
Industrial Gases - EMEA [Member]
Segment Reporting Information [Line Items]
Sales	438.3	500.8
Operating income (loss)	91.7	81.3
Depreciation and amortization	46.7	51.1
Equity affiliates' income	7.6	10.3
Total assets	3,224.5		3,323.9
Industrial Gases - Asia [Member]
Segment Reporting Information [Line Items]
Sales	413.2	398.7
Operating income (loss)	116.7	90.5
Depreciation and amortization	51.7	49.6
Equity affiliates' income	11.7	14.6
Total assets	4,155.4		4,154.0
Industrial Gases - Global [Member]
Segment Reporting Information [Line Items]
Sales	104.3	59.0
Operating income (loss)	(19.3)	(17.9)
Depreciation and amortization	2.1	4.3
Equity affiliates' income	(0.5)	0.4
Total assets	383.3		370.5
Materials Technologies [Member]
Segment Reporting Information [Line Items]
Sales	490.0	524.0
Operating income (loss)	127.2	104.6
Depreciation and amortization	19.6	24.0
Equity affiliates' income	0.4	0.6
Total assets	1,705.8		1,741.9
Energy-from-Waste [Member]
Segment Reporting Information [Line Items]
Sales	0.0	0.0
Operating income (loss)	(3.6)	(2.5)
Depreciation and amortization	0.0	0.0
Equity affiliates' income	0.0	0.0
Total assets	938.9		894.4
Corporate and other [Member]
Segment Reporting Information [Line Items]
Sales	73.9	75.3
Operating income (loss)	(5.2)	(22.7)
Depreciation and amortization	3.8	2.9
Equity affiliates' income	0.0	$ 0.0
Total assets	$ 1,178.1		$ 1,074.9