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MINERAL PROPERTY INTEREST - Mineral Property Interests (Details) - USD ($) $ in Thousands |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jun. 30, 2018 | Apr. 19, 2016 | Jun. 30, 2016 | Dec. 31, 2015 | Jun. 30, 2015 | Dec. 31, 2014 | Jun. 30, 2014 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Purchase price |  |  |  |  |  |  |  | $ 5,985 |  |
Mineral property interests |  |  |  | $ 237,245 |  |  |  | 242,640 | $ 237,245 |
Impairment charges |  |  |  |  |  |  |  |  | 50,600 | $ 353,736
Amortization of mineral property interests and asset retirement obligations |  |  |  |  |  |  |  | 2,413 | 1,288 | 1,236
Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  | 7,500 | $ 29,700 | $ 98,400 |  |  |  |
Recovery of deferred income tax |  |  | $ 10,400 | 2,200 |  | 31,600 |  |  | 31,600 |
Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  | 27,000 |  |  |  |
Recovery of deferred income tax |  |  |  |  |  | 3,200 |  |  |  |
Los Azules Copper Project |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Mineral property interests |  |  |  | 191,490 |  |  |  | 191,490 | 191,490 |
Impairment charges |  |  |  | 11,400 |  | 107,900 | $ 120,400 |  |  |
Recovery of deferred income tax |  |  |  | 1,300 |  | $ 19,300 | $ 22,500 |  |  |
Gold Bar Complex | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 20,847 | 31,391
Tonkin Properties |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Mineral property interests |  |  |  | 4,833 |  |  |  | 4,833 | 4,833 |
Tonkin Properties | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 14,939 | 25,435
Other United States Properties | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 9,611
El Gallo 1 mine |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Mineral property interests |  |  |  | 5,925 |  |  |  | 8,545 | 5,925 |
Amortization of mineral property interests and asset retirement obligations |  |  |  |  |  |  |  | 2,400 | 1,300 | 1,300
El Gallo 2 Properties |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Mineral property interests |  |  |  | 3,482 |  |  |  | 5,807 | 3,482 |
Impairment charges |  |  |  | 2,000 |  |  |  |  |  |
Limo Project | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 23,438
North Battle Mountain Complex Located in Nevada, United States | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 1,921
North Battle Mountain Properties Located In Nevada United States |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Mineral property interests |  |  |  | 785 |  |  |  | 785 | 785 |
North Battle Mountain Properties Located In Nevada United States | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 1,443 |
East Battle Mountain Properties Located In Nevada United States | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 4,060
West Battle Mountain Properties Located In Nevada United States | Nevada |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 2,567
Mexico property interests |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Amortization of mineral property interests |  |  |  |  |  |  |  | 1,900 | 800 | 800
Amortization of capitalized asset retirement costs |  |  |  |  |  |  |  |  | 500 | 500
Gold Bar Project |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Mineral property interests |  |  |  | $ 30,730 |  |  |  | 31,180 | 30,730 |
Royalty |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Required payment of gross revenue less allowable deductions to the tiered net smelter return royalty on the El Gallo 1 Mine (as a percent) |  | 3.50% |  |  |  |  |  |  |  |
Eventually reduced percentage of required payment |  | 1 |  |  |  |  |  |  |  |
Purchase price | $ 1,000 | $ 5,300 |  |  |  |  |  |  |  |
Total purchase price at closing |  | 6,300 |  |  |  |  |  |  |  |
Royalty | Non-current other liabilities |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Purchase price |  |  |  |  |  |  |  | 1,000 |  |
Royalty | El Gallo 1 mine |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Additional to mineral properties |  | 5,100 |  |  |  |  |  |  |  |
Royalty | El Gallo 2 Properties |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Additional to mineral properties |  | $ 1,200 |  |  |  |  |  |  |  |
Argentina | Los Azules Copper Project |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 11,399 | 228,301
Argentina | Other Argentina exploration properties in San Juan, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 7,817
Argentina | Cerro Mojon Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 1,971
Argentina | La Merced Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 1,891
Argentina | Cabeza de Vaca Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 877
Argentina | El Trumai Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 1,534
Argentina | Martes 13 Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 3,568
Argentina | Celestina Tenements in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 1,753
Argentina | Other Argentina exploration properties in Santa Cruz, Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | $ 7,601
Mexico |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Amortization of capitalized asset retirement costs |  |  |  |  |  |  |  | $ 500 |  |
Mexico | Property, Plant and Equipment |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | 1,972 |
Mexico | Nevada And Argentina |  |  |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  | $ 50,600 |

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