Derivative Financial Instruments (Details) $ in Thousands	Jun. 30, 2017 USD ($) oz $ / oz
Silver concentrate sales agreements [Member] | 2016 [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 1,994
Derivative average price | $ / oz	16.85
Outstanding Provisionally Priced Sales Consists of Silver | oz	118,361
Silver concentrate sales agreements [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 0
Derivative average price | $ / oz	0.00
Notional ounces | oz	0
Gold concentrates sales agreements [Member] | 2016 [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 41,176
Derivative average price | $ / oz	1,262.67
Outstanding Provisionally Priced Sales Consists of Gold | oz	32,602
Gold concentrates sales agreements [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 0
Derivative average price | $ / oz	0.00
Notional ounces | oz	0