INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE - Summary of Operating Results from MSC (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Income tax recovery	$ (1,138)	$ (2,656)
(Loss) income from investment in MSC, net of amortization	$ (212)	$ 190
Corporate Venture
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Ownership interest (as a percent)	100.00%	100.00%
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Net sales	$ 50,662	$ 48,343
Production costs applicable to sales	(43,468)	(36,699)
Net (loss) income	$ 878	$ 4,381
Ownership interest (as a percent)	49.00%	49.00%
Net income (loss)	$ 430	$ 2,147	$ (2,328)
Amortization of fair value increments	2,115	2,069	9,632
Income tax recovery	1,473	112	$ 11,916
(Loss) income from investment in MSC, net of amortization	$ (212)	$ 190

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

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee, before amortization, to which the equity method of accounting is applied.

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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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