Derivative Financial Instruments and Related Hedging Programs, Hedging Discussion (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014 mmlbs	Sep. 30, 2013 mmlbs	Dec. 31, 2013	Sep. 30, 2014 Remainder of 2014 mmlbs	Sep. 30, 2014 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 contingency features that were in a net liability position	$ 1.7		$ 1.6
Total fabricated products shipments containing fixed price terms	109.3	87.2
Firm price customer sales contracts containing price risk on anticipated purchases of primary aluminum				41.1	18.3
Principal amount of notes	$ 225.0		$ 225.0			$ 175.0