Impairment of Long Lived Assets (Details) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Sep. 29, 2015 USD ($)	Jun. 30, 2013 USD ($)
Impairment of Long Lived Assets
Property net book value	$ 11,125			$ 9,235	$ 11,125
Impairment of long lived assets				$ 0	$ 13,181
Mineral Properties Asset Group
Impairment of Long Lived Assets
Number of asset groups | item				2
Property fair value							$ 6,000
Other working capital (deficit)		$ (872)	$ (872)			$ (872)
Impairment of long lived assets		13,181
Mineral properties, net		3,718	3,718			16,899
Increase (reduction) in obsolescence reserve	$ (100)		400
Mineral Properties Asset Group | Mineral and exploration properties
Impairment of Long Lived Assets
Discounted cash flows value		0	0
Property fair value		1,400	1,400
Property net book value		1,354	1,354			13,660
Impairment of long lived assets		12,306
Mineral Properties Asset Group | Exploration properties
Impairment of Long Lived Assets
Property net book value						458
Impairment of long lived assets		458
Mineral Properties Asset Group | Buildings, plant and equipment
Impairment of Long Lived Assets
Property net book value		3,236	3,236			3,236
Mineral Properties Asset Group | Asset retirement cost
Impairment of Long Lived Assets
Property net book value						$ 417
Impairment of long lived assets		417
Velardena properties | Mineral and exploration properties
Impairment of Long Lived Assets
Impairment of long lived assets			12,800
Oxide Plant
Impairment of Long Lived Assets
Property fair value		$ 1,300	$ 1,300