Sale of Metals and Related Costs (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 item
Sale of Metals and Related Costs
Number of customers to whom marketable products were sold	5
Number of dore and precipitate customers with whom the entity entered into an agreement for passing the title to purchasers after the product is received by the refinery	1
Inventory write down charged to cost of metals sold	$ 1.6
Inventory write down charged to depreciation expense	0.3
Workforce reduction severance costs	$ 0.6