Properties, Plants, and Equipment, Net - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Kmt	Dec. 31, 2012 Kmt
Smelting Assets [Member]
Property, Plant and Equipment [Line Items]
Net carrying value of assets	$ 404	$ 310
Net carrying value of other idled smelting assets written off	44
Idle capacity of assets, units	655	547
Idled Refining Assets [Member]
Property, Plant and Equipment [Line Items]
Net carrying value of assets	$ 60	$ 68
Idle capacity of assets, units	1,216	1,277