Derivative Financial Instruments (Details) $ in Thousands	Mar. 31, 2017 USD ($) oz $ / oz
Silver concentrate sales agreements [Member] | 2016 [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 1,403
Derivative average price | $ / oz	18
Outstanding Provisionally Priced Sales Consists of Silver | oz	79,084
Silver concentrate sales agreements [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 0
Derivative average price | $ / oz	0
Notional ounces | oz	0
Gold concentrates sales agreements [Member] | 2016 [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 35,849
Derivative average price | $ / oz	1,211
Outstanding Provisionally Priced Sales Consists of Gold | oz	29,603
Gold concentrates sales agreements [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 0
Derivative average price | $ / oz	0
Notional ounces | oz	0