Derivative Instruments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Effect of mark to market valuation [Member]
Other Derivatives
Other Derivatives	$ 0.1	$ 0.5
Settlements [Member]
Other Derivatives
Other Derivatives	0.1	0
Commodity Contract [Member]
Other Derivatives
Other Derivatives	0.2	0.5
Foreign exchange hedges [Member]
Other Derivatives
Other Derivatives	$ (0.4)	$ (0.6)