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INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE (Details 3) (USD $) | 3 Months Ended | 9 Months Ended | 12 Months Ended | 3 Months Ended | 8 Months Ended | 9 Months Ended | 12 Months Ended |  | 1 Months Ended | 3 Months Ended | 1 Months Ended
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Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Dec. 31, 2012 | Sep. 30, 2013 MSC | Jun. 30, 2013 MSC | Sep. 30, 2012 MSC | Sep. 30, 2012 MSC | Sep. 30, 2013 MSC | Sep. 30, 2012 MSC | Dec. 31, 2012 MSC | Jan. 24, 2012 MSC | Oct. 31, 2013 MSC Vend-in agreement Item | Dec. 31, 2013 MSC Vend-in agreement Subsequent event | Oct. 31, 2013 MSC Hochschild Item
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sales percentage |  |  |  |  |  | 100.00% |  | 100.00% | 100.00% | 100.00% |  |  |  |  |  |
Sales |  |  |  |  |  | $ 69,662,000 |  | $ 116,299,000 | $ 212,902,000 | $ 182,031,000 |  |  |  |  |  |
Net income percentage |  |  |  |  |  | 100.00% |  | 100.00% | 100.00% | 100.00% |  |  |  |  |  |
Net income |  |  |  |  |  | 5,424,000 |  | 26,343,000 | 37,765,000 | 7,988,000 |  |  |  |  |  |
Ownership interest (as a percent) |  |  |  |  |  | 49.00% |  |  |  | 49.00% |  |  | 49.00% |  |  |
Net income on investment in MSC |  |  |  |  |  | 2,658,000 |  | 12,908,000 | 18,505,000 | 3,914,000 |  | 25,301,000 |  |  |  |
Amortization of fair value increments |  |  |  |  |  | (618,000) |  | (1,668,000) | (3,537,000) | (3,662,000) | (3,537,000) | (4,466,000) |  |  |  |
Income on investment in MSC, net of amortization | 2,040,000 | 11,240,000 | 252,000 | 14,968,000 |  | 2,040,000 |  | 11,240,000 | 14,968,000 | 252,000 |  |  |  |  |  |
Current assets | 50,920,000 |  | 50,920,000 |  | 91,918,000 | 120,200,000 |  |  |  | 120,200,000 |  |  |  |  |  |
Total assets | 973,251,000 |  | 973,251,000 |  | 1,150,937,000 | 522,400,000 |  |  |  | 522,400,000 |  |  |  |  |  |
Current liabilities | 11,392,000 |  | 11,392,000 |  | 25,195,000 | 56,400,000 |  |  |  | 56,400,000 |  |  |  |  |  |
Total liabilities | 215,554,000 |  | 215,554,000 |  | 261,346,000 | 166,800,000 |  |  |  | 166,800,000 |  |  |  |  |  |
Impairment of investment in Minera Santa Cruz S.A. |  |  | 95,878,000 |  |  |  | 95,900,000 |  |  | 95,878,000 |  |  |  |  |  |
Area of property transferred |  |  |  |  |  |  |  |  |  |  |  |  |  | 48,900 |  | 82,700
Net smelter return royalty payable (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.00% |  |
Carrying value of mining claims |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 53,200,000 |
Deferred tax liability related to mineral properties |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 17,300,000 |
Expected gain or loss to be recognized | $ 51,000 | $ 1,233,000 | $ (223,000) | $ 3,075,000 | $ 3,075,000 |  |  |  |  |  |  |  |  |  | $ 0 |

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