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MINERAL PROPERTY INTERESTS AND ASSET RETIREMENT OBLIGATIONS (Details) $ in Thousands | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2015 USD ($) item | Dec. 31, 2014 USD ($) | Jun. 30, 2014 USD ($) | Dec. 31, 2013 USD ($) | Sep. 30, 2013 USD ($) | Jun. 30, 2013 USD ($) | Dec. 31, 2015 USD ($) item | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Sep. 30, 2014 USD ($)
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | $ 237,245 | $ 287,812 |  | $ 642,968 |  |  | $ 237,245 | $ 287,812 | $ 642,968 |
Impairment charges |  |  |  |  |  |  | 50,600 | 353,736 | 62,963 |
Recovery of deferred income tax |  |  |  |  |  |  | 10,400 | 76,600 |  |
Income tax recovery |  |  |  |  |  |  | (24,560) | (107,170) | (53,365) |
Exploration costs |  |  |  |  |  |  | $ (8,798) | (11,332) | (24,829) |
Deferred tax liability related to mineral properties transferred |  | 214 |  |  |  |  |  | 214 |  |
Percentage of annual fees on surety bonds |  |  |  |  |  |  | 1.50% |  |  |
Percentage of upfront deposit on surety bonds |  |  |  |  |  |  | 10.00% |  |  |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |
Cash bonding for mineral properties in the United States | 4,800 | 4,800 |  |  |  |  | $ 4,800 | 4,800 |  | $ 4,800
Amortization of mineral property interests and asset retirement obligations |  |  |  |  |  |  | 1,288 | 1,236 | 1,530 |
Asset retirement obligation liability, beginning balance |  |  |  |  |  |  | 7,471 | 7,247 |  |
Settlements |  |  |  |  |  |  |  | (52) |  |
Accretion of liability |  |  |  |  |  |  | 429 | 407 | 461 |
Adjustment reflecting updated estimates |  |  |  |  |  |  | (116) | (131) |  |
Asset retirement obligation liability, ending balance | 7,784 | 7,471 |  | 7,247 |  |  | 7,784 | 7,471 | 7,247 |
Current portion of the asset retirement obligation | 215 | 2,427 |  |  |  |  | $ 215 | 2,427 |  |
MSC |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Additional discount |  |  |  |  |  |  | 20.00% |  |  |
Impairment charges |  |  |  |  |  |  |  | 21,200 |  |
Income tax recovery |  |  |  |  |  |  | $ 15,942 | 10,503 | $ 17,145 |
Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 29,700 | 98,400 |  |
Recovery of deferred income tax |  |  |  |  |  |  |  | 31,600 |  |
Los Azules Copper Project |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | 191,490 | 202,889 |  |  |  |  | $ 191,490 | 202,889 |  |
Impairment charges | 11,400 | 107,900 | $ 120,400 |  |  |  |  |  |  |
Recovery of deferred income tax | $ 1,300 | 19,300 | $ 22,500 |  |  |  |  |  |  |
Tonkin property and El Gallo 1 mine portion of the El Gallo Complex |  |  |  |  |  |  |  |  |  |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |
Number of most significant properties subject to reclamation obligations | item | 2 |  |  |  |  |  | 2 |  |  |
Tonkin Complex |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | $ 4,833 | 20,423 |  |  |  |  | $ 4,833 | 20,423 |  |
Impairment charges | 6,100 |  |  |  |  |  |  |  |  |
Recovery of deferred income tax | 1,700 |  |  |  |  |  |  |  |  |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |
Undiscounted estimated reclamation costs | 2,700 |  |  |  |  |  | 2,700 |  |  |
Tonkin Complex | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | $ 20,847 | $ 25,435 |  |
Tonkin Complex | Asset retirement obligation |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Credit adjusted risk free rate (as a percent) |  |  |  |  |  |  | 6.80% | 8.70% | 8.70% |
Inflation rate (as a percent) |  |  |  |  |  |  | 1.69% | 3.00% | 3.00% |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |
Fair Value Assumptions, Risk Free Interest Rate |  |  |  |  |  |  | 6.80% | 8.70% | 8.70% |
Fair Value Assumptions Inflation Rate |  |  |  |  |  |  | 1.69% | 3.00% | 3.00% |
El Gallo mine |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | 5,925 | 7,214 |  |  |  |  | $ 5,925 | $ 7,214 |  |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |
Undiscounted estimated reclamation costs | 6,800 |  |  |  |  |  | 6,800 |  |  |
Amortization of mineral property interests and asset retirement obligations |  |  |  |  |  |  | 1,300 | 1,300 |  |
Other United States Properties | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 9,611 | $ 9,497 |
Limo Complex | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 23,438 | 19,450 |
West Battle Mountain Complex | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 2,567 | 6,287 |
Exploration properties in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  | $ 27,700 |  |  |  |
Recovery of deferred income tax |  |  |  |  |  | $ 2,300 |  |  |  |
Exploration properties in Santa Cruz, Argentina | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  | 28,900 | $ 6,300 |  |  |  |  |
Recovery of deferred income tax |  |  |  | 10,100 | $ 2,200 |  |  |  |  |
Exploration properties in Santa Cruz, Argentina | Vend-in agreement | MSC |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests |  |  |  | 35,900 |  |  |  |  | 35,900 |
Deferred tax liability related to mineral properties transferred |  |  |  | 17,300 |  |  |  |  | $ 17,300 |
Mexico property interests |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Amortization of mineral property interests |  |  |  |  |  |  | 800 | 800 |  |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |
Amortization of capitalized asset retirement costs |  |  |  |  |  |  | 500 | 500 |  |
North Battle Mountain Complex Located in Nevada, United States |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | 785 | 2,227 |  |  |  |  | 785 | 2,227 |  |
Impairment charges | 1,400 |  |  |  |  |  |  |  |  |
Recovery of deferred income tax | 500 |  |  |  |  |  |  |  |  |
North Battle Mountain Complex Located in Nevada, United States | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 1,443 | 1,921 |  |
East Battle Mountain Complex Located in Nevada, United States | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 4,060 |  |
Gold Bar Complex |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | 30,730 | 51,577 |  |  |  |  | 30,730 | 51,577 |  |
Gold Bar Complex | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | $ 14,939 | $ 31,391 |  |
El Gallo in Mexico | Asset retirement obligation |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Credit adjusted risk free rate (as a percent) |  |  |  |  |  |  | 6.80% | 6.40% |  |
Inflation rate (as a percent) |  |  |  |  |  |  |  | 1.40% | 4.10% |
Changes in the asset retirement obligations |  |  |  |  |  |  |  |  |  |
Fair Value Assumptions, Risk Free Interest Rate |  |  |  |  |  |  | 6.80% | 6.40% |  |
Fair Value Assumptions Inflation Rate |  |  |  |  |  |  |  | 1.40% | 4.10% |
El Gallo 2 Properties |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | 3,482 | 3,482 |  |  |  |  | $ 3,482 | $ 3,482 |  |
Impairment charges | 2,000 |  |  |  |  |  |  |  |  |
Mineral property interest, carrying value before impairment | 2,000 |  |  |  |  |  | 2,000 |  |  |
Gold Bar Project | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 20,800 |  |  |
Tonkin Project | Nevada |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 8,900 |  |  |
Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | 191,490 | 202,889 |  | 458,203 |  |  | 191,490 | 202,889 | $ 458,203 |
Impairment charges |  |  |  |  |  |  | 11,399 | 255,313 | 27,729 |
Recovery of deferred income tax |  |  |  |  |  |  |  | 3,200 |  |
Income tax recovery |  |  |  |  |  |  | (10,759) | (74,952) | (38,015) |
Exploration costs |  |  |  |  |  |  | (1,481) | (2,453) | (14,776) |
Argentina | Los Azules Copper Project |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 11,399 | 228,301 |  |
Argentina | Telken Tenements |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 13,792 |
Argentina | Este Tenements |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 2,784 |
Argentina | Piramides Tenements |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 5,079 |
Argentina | Tobias Tenements |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 6,074 |
Argentina | Cerro Mojon Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 1,971 |  |
Argentina | La Merced Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 1,891 |  |
Argentina | Cabeza de Vaca Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 877 |  |
Argentina | El Trumai Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 1,534 |  |
Argentina | Martes 13 Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 3,568 |  |
Argentina | Property, plant and equipment |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 1,972 |  |  |
Argentina | Other Argentina exploration properties in San Juan, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 7,817 |  |
Argentina | Celestina Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 1,753 |  |
Argentina | Other Argentina exploration properties in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 7,601 |  |
Other Argentina Properties |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  | 27,000 |  |
Mexico |  |  |  |  |  |  |  |  |  |
Minerals Property Interests [Line Items] |  |  |  |  |  |  |  |  |  |
Mineral property interests | $ 9,408 | $ 10,696 |  | $ 11,984 |  |  | 9,408 | 10,696 | 11,984 |
Impairment charges |  |  |  |  |  |  | 1,972 |  |  |
Income tax recovery |  |  |  |  |  |  | (1,292) | (371) | (495) |
Exploration costs |  |  |  |  |  |  | $ (4,526) | $ (5,468) | $ (6,658) |

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