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MINERAL PROPERTY INTERESTS AND ASSET RETIREMENT OBLIGATIONS (Details) (USD $) | 3 Months Ended | 9 Months Ended | 12 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 0 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended | 13 Months Ended |  | 3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 3 Months Ended |
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Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012 | Dec. 31, 2012 | Sep. 30, 2013 Argentina | Sep. 30, 2013 Telken Tenements | Sep. 30, 2013 Este Tenements | Sep. 30, 2013 Piramides Tenements | Sep. 30, 2013 Tobias Tenements | Sep. 30, 2012 Property, plant and equipment Argentina | Sep. 30, 2012 Other United States Properties Nevada | Sep. 30, 2012 Other United States Properties Nevada | May 31, 2013 Limo Complex | Sep. 30, 2013 Limo Complex | Sep. 30, 2013 El Gallo Complex | Sep. 30, 2013 El Gallo Complex | Sep. 30, 2013 El Gallo Complex Gold equivalents oz | Sep. 30, 2013 El Gallo Complex Gold equivalents oz | Dec. 31, 2012 El Gallo Complex Gold equivalents oz | Sep. 30, 2013 El Gallo Complex Gold equivalents oz | Sep. 30, 2013 Tonkin property and El Gallo 1 mine portion of the El Gallo Complex Item | Sep. 30, 2013 West Battle Mountain Complex | Sep. 30, 2013 West Battle Mountain Complex | Sep. 30, 2013 West Battle Mountain Complex Nevada | Sep. 30, 2013 West Battle Mountain Complex Nevada | Jun. 30, 2013 Exploration properties in Santa Cruz, Argentina | Sep. 30, 2013 Exploration properties in Santa Cruz, Argentina | Jun. 30, 2013 Exploration properties in Santa Cruz, Argentina MSC | Sep. 30, 2013 Tonkin Complex
Mineral Property Interests |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Quantity produced (in ounces) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8,027 | 23,370 | 6,949 | 30,319 |  |  |  |  |  |  |  |  |
Number of most significant properties subject to reclamation obligations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |
Undiscounted estimated reclamation costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,600,000 | $ 4,600,000 |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,800,000
Cash bonding for mineral properties in the United States | 5,183,000 |  | 5,183,000 |  | 5,183,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization of mineral property interests and asset retirement obligations |  |  | 1,244,000 |  |  |  |  |  |  |  |  |  |  |  |  | 300,000 | 1,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Price of mineral property interests under the sale agreement |  |  |  |  |  |  |  |  |  |  |  |  |  | 800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Carrying value of mining claims |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,200,000 |  |  |  |  |  |  |  |  | 6,300,000 | 6,300,000 |  |  |  |  |  |
Loss on disposal |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,400,000 | 3,900,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax on mining real estate property (as a percent) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1.00% |  | 1.00% |
Impairment charges | 6,287,000 | 2,902,000 | 34,016,000 | 3,081,000 |  | 27,729,000 | 13,792,000 | 2,784,000 | 5,079,000 | 6,074,000 | 179,000 | 2,902,000 | 2,902,000 |  |  |  |  |  |  |  |  |  |  |  | 6,287,000 | 6,287,000 | 27,700,000 |  |  |
Deferred income tax |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,500,000 |  |  |  |  |  |  |  |  | 2,200,000 |  |  |  |  | 2,300,000 |  |
Net impairment charge |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,100,000 | 4,100,000 |  |  |  | 25,400,000 |  |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset retirement obligation liability - opening balance |  |  | 6,359,000 | 6,253,000 | 6,253,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Settlements |  |  | (56,000) |  | (47,000) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accretion of liability | 113,000 | 110,000 | 347,000 | 342,000 | 447,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Adjustment reflecting updated estimates |  |  | (29,000) |  | (294,000) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Asset retirement obligation liability - ending balance | 6,616,000 |  | 6,616,000 |  | 6,359,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Current portion of the asset retirement obligation | $ 1,351,000 |  | $ 1,351,000 |  | $ 130,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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