INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Current assets	$ 39,701us-gaap_AssetsCurrent	$ 46,771us-gaap_AssetsCurrent
Total assets	522,958us-gaap_Assets	923,066us-gaap_Assets	1,150,937us-gaap_Assets
Current liabilities	24,081us-gaap_LiabilitiesCurrent	11,189us-gaap_LiabilitiesCurrent
Total liabilities	81,743us-gaap_Liabilities	176,299us-gaap_Liabilities
Impairment of investment in MSC	21,162	95,878
Depreciation expense	979	942	1,033
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Current assets	113,300
Total assets	540,600
Current liabilities	67,000
Total liabilities	179,400
Impairment of investment in MSC	21,162	95,878
Dividend received	9,483	1,826
MSC \| Current Period Values Excluding Fair Value Increments And Impairment Charge
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Current assets	111,500
Total assets	311,500
Current liabilities	67,000
Total liabilities	$ 102,700

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold, or consumed within one year (or the normal operating cycle, if longer). Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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