Inventories (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Inventories
Metals inventory	$ 119	$ 477
In-process inventory	141	307
Material and supplies	826	713
Inventories	1,086	1,497
Inventory write down charged to cost of metals sold	$ 200	1,200
Inventory write down charged to depreciation expense		$ 700