The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44D

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Derivative Financial Instruments and Related Hedging Programs, Hedging Discussion (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 mmlbs	Jun. 30, 2012 mmlbs	Dec. 31, 2012	Jun. 30, 2013 Remainder of 2013 mmlbs	Jun. 30, 2013 2014 mmlbs	Jun. 30, 2013 2015 mmlbs	Mar. 29, 2010 Convertible Notes
Derivative Financial Instruments and Related Hedging Programs (Textuals) [Abstract]
Aggregate fair value of derivative instruments that contain credit-risk-related contingent features that were in a net liability position	$ 6.5
Total fabricated products shipments containing fixed price terms	58.2	91.5
Firm price customer sales contracts containing price risk on anticipated purchases of primary aluminum				54.7	9.2	1.3
Principal amount of notes	$ 225.0		$ 225.0				$ 175.0