Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014
Property, plant and equipment
Property, plant and equipment, gross	$ 36,057	$ 36,057	$ 50,255
Impairment Charges	13,181	13,181
Less: Accumulated depreciation and amortization	(24,259)	(24,259)	(21,224)
Property, plant and equipment, net	11,798	11,798	29,031
Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	36,057	36,057
Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	49,238	49,238
Velardena properties | Impairment adjustment
Property, plant and equipment
Impairment Charges		13,181
Mineral properties
Property, plant and equipment
Property, plant and equipment, gross	9,630	9,630	22,397
Mineral properties | Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	9,630	9,630
Mineral properties | Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	21,936	21,936
Mineral properties | Velardena properties | Impairment adjustment
Property, plant and equipment
Impairment Charges		12,306
Exploration properties
Property, plant and equipment
Property, plant and equipment, gross	2,543	2,543	2,743
Exploration properties | Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	2,543	2,543
Exploration properties | Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	3,001	3,001
Exploration properties | Velardena properties | Impairment adjustment
Property, plant and equipment
Impairment Charges		458
Royalty properties
Property, plant and equipment
Property, plant and equipment, gross	200	200	200
Royalty properties | Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	200	200
Royalty properties | Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	200	200
Buildings
Property, plant and equipment
Property, plant and equipment, gross	4,377	4,377	4,378
Buildings | Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	4,377	4,377
Buildings | Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	4,377	4,377
Mining equipment and machinery
Property, plant and equipment
Property, plant and equipment, gross	17,181	17,181	17,694
Mining equipment and machinery | Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	17,181	17,181
Mining equipment and machinery | Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	17,181	17,181
Other furniture and equipment
Property, plant and equipment
Property, plant and equipment, gross	841	841	841
Other furniture and equipment | Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	841	841
Other furniture and equipment | Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	841	841
Asset retirement cost
Property, plant and equipment
Property, plant and equipment, gross	1,285	1,285	$ 2,002
Asset retirement cost | Velardena properties
Property, plant and equipment
Property, plant and equipment, gross	1,285	1,285
Asset retirement cost | Velardena properties | Prior to impairment
Property, plant and equipment
Property, plant and equipment, gross	$ 1,702	1,702
Asset retirement cost | Velardena properties | Impairment adjustment
Property, plant and equipment
Impairment Charges		417
Mineral and exploration properties | Velardena properties
Property, plant and equipment
Impairment Charges		$ 12,800