Derivative Financial Instruments (Details) $ in Thousands	Sep. 30, 2017 USD ($) oz $ / oz
Silver concentrate sales agreements [Member] | 2017 [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 3,915
Derivative average price | $ / oz	16.86
Outstanding Provisionally Priced Sales Consists of Silver | oz	232,200
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] | 2017 [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 33,887
Derivative average price | $ / oz	1,299.00
Outstanding Provisionally Priced Sales Consists of Gold | oz	26,087
Gold concentrates sales agreements [Member] | Thereafter [Member]
Derivative instruments Settlement
Derivative, notional amount | $	$ 0
Derivative average price | $ / oz	0.00
Notional ounces | oz	0