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v3.19.1

INVESTMENTS (Tables) | 3 Months Ended
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Mar. 31, 2019
INVESTMENTS |
Summary of investment portfolio |
|  |  |  | Additions |  | Net gains |  | Disposals |  | Unrealized |  | Fair value
|  | Opening |  | during |  | (loss) on |  | during |  | gain (loss) on |  | end of the
As of March 31, 2019 |  | balance |  | period |  | securities sold |  | period |  | securities held |  | period
Marketable equity securities |  | $ | 2,718 |  | $ | 264 |  | $ | — |  | $ | — |  | $ | 605 |  | $ | 3,587
Warrants |  |  | 413 |  |  | — |  |  | — |  |  | — |  |  | 222 |  |  | 635
Investments |  | $ | 3,131 |  | $ | 264 |  | $ | — |  | $ | — |  | $ | 827 |  | $ | 4,222
|  |  |  | Additions |  | Net gains |  | Disposals |  | Unrealized |  | Fair value
|  | Opening |  | during |  | (loss) on |  | during |  | gain (loss) on |  | end of the
As of March 31, 2018 |  | balance |  | period |  | securities sold |  | period |  | securities held |  | period
Marketable equity securities |  | $ | 6,404 |  | $ | — |  | $ | (734) |  | $ | (2,663) |  | $ | (1,137) |  | $ | 1,870
Warrants |  |  | 1,567 |  |  | — |  |  | — |  |  | — |  |  | (864) |  |  | 703
Investments |  | $ | 7,971 |  | $ | — |  | $ | (734) |  | $ | (2,663) |  | $ | (2,001) |  | $ | 2,573

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- Definition A tabular disclosure of the investment portfolio, which consists of the marketable securities and warrants. + References No definition available. + Details
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Namespace Prefix: | mux_
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- References No definition available. + Details
Name: | us-gaap_InvestmentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration