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Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure Of Significant Accounting Policies [line items] |  |  |
Impairment loss | $ 0 |  |
Variation potential percentage benchmark | 25.00% |  |
Variation potential percentage globally | 90.00% |  |
Confidence percentage related to inferred tonnes, grade, metal content recoverability | 95.00% |  |
Inferred recoverability of resources percentage, benchmark | 75.00% |  |
Top of range [member] |  |  |
Disclosure Of Significant Accounting Policies [line items] |  |  |
Conversion factors related to inferred resources | 80.00% | 80.00% |
Machinery and Equipment [member] |  |  |
Disclosure Of Significant Accounting Policies [line items] |  |  |
Depreciation method, property, plant and equipment | Straight line |  |
Useful lives or depreciation rates, property, plant and equipment | 3‑15 years |  |
Mineral Properties [member] |  |  |
Disclosure Of Significant Accounting Policies [line items] |  |  |
Depreciation method, property, plant and equipment | Declining balance |  |
San Jose M&I Property [member] |  |  |
Disclosure Of Significant Accounting Policies [line items] |  |  |
Conversion factors related to inferred resources | 90.00% | 90.00% |
Percentage of inferred resources | 21.00% | 23.00% | 28.00%
Caylloma M&I Property [member] |  |  |
Disclosure Of Significant Accounting Policies [line items] |  |  |
Percentage of inferred resources | 48.00% | 60.00% | 38.00%
Restricted Share Units [member] |  |  |
Disclosure Of Significant Accounting Policies [line items] |  |  |
vesting period | 3 years |  |
Description of vesting requirements for share-based payment arrangement | RSUs are settled in either cash or equity, as determined by the Company's Board of Directors at the grant date and typically vest over three years. |  |
Performance Share Units [member] |  |  |
Disclosure Of Significant Accounting Policies [line items] |  |  |
vesting period | 3 years |  |
Description of vesting requirements for share-based payment arrangement | Performance Share Units are performance-based awards for the achievement of specified performance metrics by specified deadlines and are settled in either cash or equity, as determined by the Company's Board of Directors at the grant date and typically vest over three years. |  |

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