INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE (Details) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Recovery of income taxes	$ 18,957,000	$ 6,463,000
Income on investment in MSC, net of amortization	7,029,000	(237,000)
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Net income on investment in MSC	3,029,000	1,196,000	2,126,000
Ownership interest (as a percent)	49.00%	49.00%
Net income	6,182,000	2,440,000
Amortization of fair value increments, before tax	1,800,000
Recovery of income taxes	5,800,000
Amortization of fair value increments, net of tax	4,000,000	(1,433,000)	(1,280,000)
Income on investment in MSC, net of amortization	7,029,000	(237,000)
Equity method investment, overstatement of income from prior year recorded in current period		3,900,000
Entity's share of income in investee, understatement of income from prior year recorded in current period		$ 1,900,000

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

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

+ References

No definition available.

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Represents the overstatement of after-tax net income, relating to the prior year, reported by an equity method investment of the entity which was deemed an immaterial error.

+ References

No definition available.

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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.

+ References

No definition available.

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Represents the overstatement of the entity's proportionate share of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied related to the prior year.

+ References

No definition available.

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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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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