Shares received as consideration for disposal group.

No definition available.

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Data Type:	xbrli:sharesItemType
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- Definition

Shares received as consideration for disposal group representing percentage of shares issued and outstanding of the acquiree.

+ References

No definition available.

+ Details

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- Definition

Warrants received as consideration for disposal group.

+ References

No definition available.

+ Details

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Namespace Prefix:	mux_
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Period Type:	instant

- Definition

The number of projects sold.

+ References

No definition available.

+ Details

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Namespace Prefix:	mux_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644

+ Details

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Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=mux_ProjectsInNevadaMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=mux_ProjectsInNevadaLimousineButteAndCedarWashMember
Namespace Prefix:
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- Details

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INVESTMENTS (Details) $ / shares in Units, $ in Thousands		12 Months Ended
INVESTMENTS (Details) $ / shares in Units, $ in Thousands	Jun. 23, 2021 USD ($) project $ / shares shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Investments
Number of common shares \| shares	4,963,455
Warrants received \| shares	2,481,727
Proceeds from sale of investments		$ 1,266	$ 6,769
Disposal Group \| Projects in Nevada
Investments
Cash consideration received	$ 500
Percentage of common shares received	10.00%
Price per common share for each warrant \| $ / shares	$ 0.60
Disposal Group \| Projects in Nevada, Limousine Butte and Cedar Wash
Investments
Number of projects sold \| project	2
Marketable equity securities
Investments
Proceeds from sale of investments		$ 1,300	$ 6,800