INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE - Summary of Operating Results from MSC (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Income taxes recovery	$ 15,369	$ 3,749	$ 24,560
(Loss) income from investment in MSC, net of amortization	$ (44)	$ 12,951	$ 2,414
Corporate Venture
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Ownership interest (as a percent)	100.00%	100.00%	100.00%
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Net sales	$ 227,093	$ 235,961	$ 186,095
Production costs applicable to sales	(177,180)	(173,679)	(158,615)
Net (loss) income	$ (4,750)	$ 32,574	$ (5,835)
Ownership interest (as a percent)	49.00%	49.00%	49.00%
Net income (loss)	$ (2,328)	$ 15,961	$ (2,859)
Amortization of fair value increments	9,632	12,274	10,669
Income taxes recovery	(11,916)	(9,264)	(15,942)
(Loss) income from investment in MSC, net of amortization	$ (44)	$ 12,951	$ 2,414

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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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