XML 53 R43.htm IDEA: XBRL DOCUMENT
v3.23.3

INVESTMENTS - Activity in Investments (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Investments rollforward |  |  |
Opening balance | $ 1,295 | $ 1,806 | $ 1,806
Additions/transfers during the period | 33,907 |  |
Unrealized gain on securities held | 15,651 | (375) | (511)
Ending balance | 40,833 |  | 1,295
Marketable equity securities |  |  |
Investments rollforward |  |  |
Opening balance | 1,133 | 1,644 | 1,644
Additions/transfers during the period | 33,907 |  |
Unrealized gain on securities held |  |  | (511)
Ending balance |  |  | 1,133
Warrants |  |  |
Investments rollforward |  |  |
Opening balance | $ 162 | $ 162 | 162
Ending balance |  |  | $ 162

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | mux_InvestmentsRollforward
Namespace Prefix: | mux_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash flow for purchase of available for sale and trading securities. + References No definition available. + Details
Name: | mux_PaymentsToAcquireAvailableForSaleAndTradingSecurities
Namespace Prefix: | mux_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org//1943274/2147483467/210-10-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1A -Publisher FASB -URI https://asc.fasb.org//1943274/2147482736/825-10-45-1A + Details
Name: | us-gaap_EquitySecuritiesFvNi
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of unrealized gain (loss) on investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -SubTopic 10 -Topic 230 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482740/230-10-45-28 + Details
Name: | us-gaap_UnrealizedGainLossOnInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_DebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=mux_WarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |