Derivatives and Other Financial Instruments - Schedule of Fair Value Gains and Losses on Derivatives Contracts Recorded in Earnings (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	$ 20	$ 13	$ 39
Aluminum Contracts [Member] | Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	(9)		(13)
Aluminum Contracts [Member] | Other Income, Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	27	16	13
Embedded Credit Derivative [Member] | Other Income, Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	8	(3)	(5)
Energy Contracts [Member] | Other Income, Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives			47
Foreign Exchange Contracts [Member] | Other Income, Net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Earnings on Derivatives	$ (6)		$ (3)