XML 66 R55.htm IDEA: XBRL DOCUMENT
v3.21.2

SHAREHOLDERS' EQUITY (Details) - USD ($) |  |  |  |  | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Feb. 09, 2021 | Jan. 29, 2021 | Dec. 31, 2020 | Sep. 10, 2020 | Jun. 30, 2021 | Jun. 30, 2021 | Dec. 31, 2020 | Jun. 29, 2021
Common stock, shares authorized |  |  |  |  | 675,000,000 | 675,000,000 |  | 500,000,000
Net proceeds |  |  |  |  |  | $ 29,875,000 |  |
Sale of common stock for cash, net of issuance costs |  |  |  |  |  | 29,875,000 |  |
November 2019 Offering |  |  |  |  |  |  |  |
Outstanding warrants |  |  |  |  | $ 21,706,250 | 21,706,250 |  |
March 2019 Offering |  |  |  |  |  |  |  |
Outstanding warrants |  |  |  |  | 8,064,516 | 8,064,516 |  |
Canadian Exploration Expenditures |  |  |  |  |  |  |  |
Gross proceeds |  |  |  |  |  |  | $ 20,200,000 |
Equity Financing In February 2021 |  |  |  |  |  |  |  |
Number of units issued | 30,000,000 |  |  |  |  |  |  |
Price per unit | $ 1.05 |  |  |  |  |  |  |
Gross proceeds | $ 31,500,000 |  |  |  |  | $ 31,500,000 |  |
Net proceeds | 29,900,000 |  |  |  |  |  |  |
Issuance costs | $ 1,700,000 |  |  |  |  |  |  |
Common Stock and Additional Paid-in Capital |  |  |  |  |  |  |  |
Number of units issued |  |  |  |  |  | 30,000,000 |  |
Net proceeds |  |  |  |  |  | $ 29,875,000 |  |
Flow Through Common Shares | Canadian Development Expenses |  |  |  |  |  |  |  |
Number of units issued |  | 12,600,600 |  |  |  |  |  |
Price per unit |  | $ 1.01 |  |  |  |  |  |
Gross proceeds |  | $ 12,700,000 |  |  |  | 12,700,000 |  |
Net proceeds |  | 12,000,000.0 |  |  |  |  |  |
Issuance costs |  | 700,000 |  |  |  |  |  |
Net proceeds allocated to the sale of tax benefits |  | 1,200,000 |  |  |  |  |  |
Sale of common stock for cash, net of issuance costs |  | $ 10,800,000 |  |  |  |  |  |
Flow Through Common Shares | Canadian Exploration Expenditures |  |  |  |  |  |  |  |
Number of units issued |  |  | 7,669,900 | 6,298,166 |  |  |  |
Price per unit |  |  | $ 1.28 | $ 1.65 |  |  | $ 1.28 |
Gross proceeds |  |  | $ 9,800,000 | $ 10,400,000 |  |  |  |
Net proceeds |  |  | 9,800,000 | 9,800,000 |  |  |  |
Issuance costs |  |  | 0 | 600,000 |  |  |  |
Net proceeds allocated to the sale of tax benefits |  |  | 2,100,000 | 2,000,000.0 |  |  |  |
Sale of common stock for cash, net of issuance costs |  |  | $ 7,700,000 | $ 7,800,000 |  |  |  |
Exploration expenditures |  |  |  |  | $ 5,800,000 | $ 7,700,000 | $ 1,900,000 |

X
- Definition The net proceeds allocated to the sale of tax benefits. + References No definition available. + Details
Name: | mux_SaleOfTaxBenefits
Namespace Prefix: | mux_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Gross equity impact of the value of new stock issued during the period. + References No definition available. + Details
Name: | mux_StockIssuedDuringPeriodValueNewIssuesGross
Namespace Prefix: | mux_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The maximum number of common shares permitted to be issued by an entity's charter and bylaws. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockSharesAuthorized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Exploration expenses (including prospecting) related to oil and gas producing entities and would be included in operating expenses of that entity. Costs incurred in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing oil and gas reserves, including costs of drilling exploratory wells and exploratory-type stratigraphic test wells. Exploration costs may be incurred both before acquiring the related property (sometimes referred to in part as prospecting costs) and after acquiring the property. Principal types of exploration costs, which include depreciation and applicable operating costs of support equipment and facilities and other costs of exploration activities, are: (i) Costs of topographical, geographical and geophysical studies, rights of access to properties to conduct those studies, and salaries and other expenses of geologists, geophysical crews, and others conducting those studies. Collectively, these are sometimes referred to as geological and geophysical or "G&G" costs. (ii) Costs of carrying and retaining undeveloped properties, such as delay rentals, ad valorem taxes on properties, legal costs for title defense, and the maintenance of land and lease records. (iii) Dry hole contributions and bottom hole contributions. (iv) Costs of drilling and equipping exploratory wells. (v) Costs of drilling exploratory-type stratigraphic test wells. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62136-109447 + Details
Name: | us-gaap_ExplorationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash outflow for cost incurred directly with the issuance of an equity security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfStockIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow from the additional capital contribution to the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Price of a single share of a number of saleable stocks of a company. + References No definition available. + Details
Name: | us-gaap_SharePrice
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodValueNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price. + References No definition available. + Details
Name: | us-gaap_WarrantsAndRightsOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_PlanNameAxis=mux_November2019OfferingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PlanNameAxis=mux_March2019OfferingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mux_CanadianExplorationExpendituresMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=mux_EquityFinancingInFebruary2021Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=mux_CommonStockAndAdditionalPaidInCapitalMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=mux_IssuanceOfFlowThroughCommonSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mux_CanadianDevelopmentExpensesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |