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INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE (Details) | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended | 1 Months Ended | 3 Months Ended
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Jun. 30, 2014 USD ($) | Jun. 30, 2013 USD ($) | Jun. 30, 2014 USD ($) | Jun. 30, 2013 USD ($) | Jun. 30, 2014 Minera Santa Cruz S A [Member] USD ($) | Jun. 30, 2013 Minera Santa Cruz S A [Member] USD ($) | Mar. 31, 2013 Minera Santa Cruz S A [Member] USD ($) | Jun. 30, 2014 Minera Santa Cruz S A [Member] USD ($) | Jun. 30, 2013 Minera Santa Cruz S A [Member] USD ($) | Dec. 31, 2013 Minera Santa Cruz S A [Member] USD ($) | Jul. 31, 2014 Minera Santa Cruz S A [Member] Scenario Forecast [Member] USD ($) | Jul. 31, 2014 Minera Santa Cruz S A [Member] Scenario Forecast [Member] ARS | Sep. 30, 2014 Minera Santa Cruz S A [Member] Scenario Forecast [Member] USD ($) | Sep. 30, 2014 Minera Santa Cruz S A [Member] Scenario Forecast [Member] ARS | Dec. 31, 2013 Minera Santa Cruz S A [Member] Exploration Properties Located In Santa Cruz Province Argentina [Member] Vend In Agreement [Member] USD ($)
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest (as a percent) |  |  |  |  | 49.00% | 49.00% |  | 49.00% | 49.00% |  |  |  |  |  |
Income (loss) on investment in Minera Santa Cruz S.A. (net of amortization) | $ (2,438,000) | $ (1,551,000) | $ 4,591,000 | $ (1,788,000) | $ (2,438,000) | $ (1,551,000) |  | $ 4,591,000 | $ (1,788,000) |  |  |  |  |  |
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 |  |  |  |  |  |
Impairment of investment in MSC |  | 95,878,000 |  | 95,878,000 |  | 95,900,000 |  |  | 95,900,000 | 95,878,000 |  |  |  |  |
Carrying value of properties, net of tax |  |  |  |  |  |  |  |  |  | 35,857,000 |  |  |  |  | 35,900,000
Deferred tax liability related to mineral properties transferred |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 17,300,000
(Gain) loss on sale of assets | (18,000) | 6,791,000 | (18,000) | 6,791,000 |  |  |  |  |  |  |  |  |  |  | 0
Dividends received |  |  | $ 7,113,000 |  | $ 3,200,000 | $ 0 |  | $ 7,100,000 | $ 0 |  | $ 1,000,000 | 8,100,000 | $ 1,000,000 | 8,100,000 |

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