Derivative Financial Instruments and Related Hedging Programs (Details1) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Summary Of Realized And Unrealized Gains Losses
Total realized gains (losses)	$ 4.8	$ (1.2)	$ 7.9	$ (2.0)
Total unrealized gains (losses)	(13.1)	(18.1)	(7.1)	(17.9)
Bifurcated Conversion Feature [Member] | Hedges Relating to Notes [Member]
Summary Of Realized And Unrealized Gains Losses
Total unrealized gains (losses)	(12.0)	6.5	(8.3)	6.5
Call Option [Member] | Hedges Relating to Notes [Member]
Summary Of Realized And Unrealized Gains Losses
Total unrealized gains (losses)	8.4	(5.6)	6.4	(5.6)
Aluminum Contracts [Member]
Summary Of Realized And Unrealized Gains Losses
Total realized gains (losses)	5.8	(1.0)	10.3	(1.7)
Total unrealized gains (losses)	(9.7)	(19.4)	(6.6)	(16.0)
Natural Gas [Member]
Summary Of Realized And Unrealized Gains Losses
Total realized gains (losses)	(1.0)	(0.2)	(2.4)	(0.3)
Total unrealized gains (losses)	0.3	0.4	1.5	(2.8)
Electricity [Member]
Summary Of Realized And Unrealized Gains Losses
Total unrealized gains (losses)	$ (0.1)		$ (0.1)