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Derivative Financial Instruments and Related Hedging Programs, Realized and Unrealized Gains and Losses Table (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Summary Of Realized And Unrealized Gains Losses
Total realized gains (losses)	$ 0.5	$ (1.2)	$ 8.4	$ (3.2)
Total unrealized (losses) gains	(12.7)	10.9	(19.8)	(7.1)
Aluminum Commodity [Member]
Summary Of Realized And Unrealized Gains Losses
Total realized gains (losses)	1.6	(0.9)	11.9	(2.6)
Total unrealized (losses) gains	(14.8)	17.1	(21.4)	1.1
Natural Gas [Member]
Summary Of Realized And Unrealized Gains Losses
Total realized gains (losses)	(1.1)	(0.3)	(3.5)	(0.6)
Total unrealized (losses) gains	(0.9)	(2.4)	0.6	(5.2)
Electricity [Member]
Summary Of Realized And Unrealized Gains Losses
Total unrealized (losses) gains	(1.1)	0	(1.2)	0
Hedges Relating to Notes [Member] | Call Options [Member]
Summary Of Realized And Unrealized Gains Losses
Total unrealized (losses) gains	(16.6)	10.3	(10.2)	4.7
Hedges Relating to Notes [Member] | Bifurcated Conversion Feature [Member]
Summary Of Realized And Unrealized Gains Losses
Total unrealized (losses) gains	$ 20.7	$ (14.1)	$ 12.4	$ (7.7)

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Summary Of Realized And Unrealized Gains Losses Abstract.

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The amount of net gains and losses recognized in income during the period on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges, on derivative instruments designated and qualifying as hedging instruments in cash flow hedges, and on derivative instruments not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



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