INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE - Summary of Operating Results from MSC (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Income taxes recovery	$ 564	$ 607	$ 3,067	$ 3,330
Loss income from investment in MSC, net of amortization	(462)	4,693	(535)	13,789
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Net sales	52,722	72,116	161,900	182,769
Production costs applicable to sales	(43,596)	(49,345)	(132,710)	(125,904)
Net income (loss)	$ 707	$ 12,072	$ 3,962	$ 31,293
Ownership interest (as a percent)	49.00%	49.00%	49.00%	49.00%
Net income (loss)	$ 346	$ 5,916	$ 1,941	$ 15,334	$ 15,961
Amortization of fair value increments	(2,469)	(2,914)	(6,967)	(9,370)	(12,274)
Income taxes recovery	1,661	1,691	4,491	7,825	$ 9,264
Loss income from investment in MSC, net of amortization	$ (462)	$ 4,693	$ (535)	$ 13,789

Represents the amortization of fair value increments from the equity method investments.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The amount of the cost of sales reported by an equity method investment of the entity.

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The amount of net income (loss) reported by an equity method investment of the entity.

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The amount of revenue from sale of goods and services reduced by sales returns, allowances, and discounts reported by an equity method investment of the entity.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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