Inventories (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Inventory, Net [Abstract]
Raw materials	$ 68,091		$ 40,725
Work-in-process	22,286		15,259
Finished goods	12,834		9,753
Operating and other supplies	128,294		94,188
Inventories (1)	$ 231,505	[1]	$ 159,925	[1]

[1] The balance at September 30, 2013 includes inventory maintained at the recently acquired Sebree smelter. See Note 2 Acquisition of Sebree aluminum smelter for additional information about the Sebree acquisition.