Cost Reduction Plan (Charges Related To The Businesses At The Segment Level) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Cost Reduction Plan [Line Items]
Severance and Other Benefits	$ 80.8		$ 80.8
Asset Impairments	6.0		6.0
Total	86.8		86.8
Merchant Gases [Member]
Cost Reduction Plan [Line Items]
Severance and Other Benefits	71.3		71.3
Asset Impairments	6.0		6.0
Total	77.3		77.3
Tonnage Gases [Member]
Cost Reduction Plan [Line Items]
Severance and Other Benefits	3.8		3.8
Total	3.8		3.8
Electronics And Performance Materials [Member]
Cost Reduction Plan [Line Items]
Severance and Other Benefits	5.7		5.7
Total	$ 5.7		$ 5.7