Derivatives And Other Financial Instruments (Narrative) (Details)	12 Months Ended
	Dec. 31, 2011 USD ($) MT	Dec. 31, 2010 USD ($)	Aug. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Dec. 31, 2009 CAD	Dec. 31, 2011 Level 3 [Member] USD ($)	Dec. 31, 2010 Level 3 [Member] USD ($)	Dec. 31, 2011 Six-Year Natural Gas Supply Contract [Member] USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net unrealized loss on derivative contracts						$ 618,000,000	$ 779,000,000	$ 5,000,000
Amount of aluminum kmt designated as fair value hedges	419,000
Face amount of debt the hedges effectively convert from fixed to floating through 2018	515,000,000
Notional amount interest rate swaps	550,000,000	825,000,000	825,000,000
Gain on termination of interest rate swaps	33,000,000	28,000,000
Forward contract to purchase to mitigate the foreign currency risk related to a Canadian-denominated loan due in 2014				$ 57,000,000	58,000,000