Other Assets (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Other Assets [Line Items]
Other Assets	$ 445	$ 220
Other Assets, Total	10,868	13,837
Bauxite raw materials | Inventories
Other Assets [Line Items]
Inventory, Raw Materials	9,949	13,143
Bauxite raw materials | Prepayments
Other Assets [Line Items]
Inventory, Raw Materials	$ 474	$ 474