XML 78 R56.htm IDEA: XBRL DOCUMENT
v3.8.0.1

MINERAL PROPERTY INTEREST - Mineral Property Interests (Details) - USD ($) $ in Thousands |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Jun. 30, 2018 | Apr. 19, 2016 | Dec. 31, 2015 | Jun. 30, 2015 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Aug. 25, 2017
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | $ 293,437 | $ 242,640 |  |
Payments to Acquire Mining Assets |  |  |  |  | 3,492 | 5,985 |  |
Additional to mineral properties |  |  |  |  | 3,300 | 0 |  |
Impairment charges |  |  |  |  | 711 |  | $ 50,600 |
Amortization of mineral property interests and asset retirement obligations |  |  |  |  | 3,198 | 2,413 | 1,288 |
Nevada |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  | $ 7,500 | $ 29,700 |  |  |  |
Deferred Income Tax on Impairment of Mineral Properties |  |  | 2,200 | $ 10,400 |  |  |  |
Black Fox |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 11,364 |  |  |
Amortization of mineral property interests and asset retirement obligations |  |  |  |  | 900 | 0 | 0 |
Lexam VG Gold |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 41,595 |  |  |
Los Azules Copper Project |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 191,490 | 191,490 |  |
Impairment charges |  |  | 11,400 |  |  |  |  |
Deferred Income Tax on Impairment of Mineral Properties |  |  | 1,300 |  |  |  |  |
Gold Bar Complex | Nevada |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 20,847 |
Tonkin Properties |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 4,833 | 4,833 |  |
Tonkin Properties | Nevada |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 14,939 |
El Gallo 1 mine |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 6,246 | 8,545 |  |
Amortization of mineral property interests and asset retirement obligations |  |  |  |  | 2,300 | 2,400 | 1,300 |
El Gallo 2 project |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 5,807 | 5,807 |  |
Impairment charges |  |  | $ 2,000 |  | 700 |  |  |
North Battle Mountain Complex Located in Nevada, United States | Nevada |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 1,443 |
North Battle Mountain Properties Located In Nevada United States |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 785 | 785 |  |
Gold Bar project |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  | 31,317 | 31,180 |  |
Royalty |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Required payment of gross revenue less allowable deductions to the tiered net smelter return royalty on the El Gallo 1 Mine (as a percent) |  | 3.50% |  |  |  |  |  |
Eventually reduced percentage of required payment |  | 1 |  |  |  |  |  |
Total purchase price at closing |  | $ 6,300 |  |  |  |  |  |
Payments to Acquire Mining Assets | $ 1,000 | 5,300 |  |  |  |  |  |
Royalty | Other Noncurrent Liabilities [Member] |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Payments to Acquire Mining Assets |  |  |  |  | 1,000 |  |  |
Royalty | El Gallo 1 mine |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Additional to mineral properties |  | 5,100 |  |  |  |  |  |
Royalty | El Gallo 2 project |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Additional to mineral properties |  | $ 1,200 |  |  |  |  |  |
Black Fox |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Mineral property interests |  |  |  |  |  |  |  | $ 8,954
Argentina | Los Azules Copper Project |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | 11,399 |
Mexico |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  | $ 711 |  |  |
Mexico | Property, Plant and Equipment |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  | $ 1,972 |
Mexico | Nevada And Argentina |  |  |  |  |  |  |  |
Mineral Property Interests |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  | $ 50,600 |  |

X
- Definition Addition to mineral properties. + References No definition available. + Details
Name: | mux_AdditionalMineralProperties
Namespace Prefix: | mux_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the amount of deferred income tax recovery on impairment of mineral properties. + References No definition available. + Details
Name: | mux_DeferredIncomeTaxOnImpairmentOfMineralProperties
Namespace Prefix: | mux_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Represents the amount of amortization expense related to the mineral property interests and capitalized asset retirement costs. + References No definition available. + Details
Name: | mux_MineralPropertyInterestsAndAssetRetirementObligationsAmortization
Namespace Prefix: | mux_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Mineral Property Interests [Line Items] + References No definition available. + Details
Name: | mux_MineralsPropertyInterestsLineItems
Namespace Prefix: | mux_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The total cash outflow from the purchase of mining and mining related assets during the period. Includes purchase price at closing and a deferred payment. + References No definition available. + Details
Name: | mux_PaymentsToAcquireMiningAssetsTotal
Namespace Prefix: | mux_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The required payment of gross revenue less allowable deductions to the tiered net smelter return royalty (the “Royalty”) on the El Gallo 1 Mine. + References No definition available. + Details
Name: | mux_PercentageGrossRevenueLessAllowableDeductionsPreviouslyRequiringPayment
Namespace Prefix: | mux_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The eventually reduced percentage of required payment of gross revenue less allowable deductions to the tiered net smelter return royalty (the “Royalty”) on the El Gallo 1 Mine. + References No definition available. + Details
Name: | mux_ReducedPercentageOfGrossRevenueLessAllowableDeductionsPreviouslyRequiringPayment
Namespace Prefix: | mux_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Mineral properties, net of adjustments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 360 -Section 25 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=96866604&loc=d3e64895-109465 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
Name: | us-gaap_MineralPropertiesNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The cash outflow from the purchase of mining and mining related assets during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireMiningAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_SubsegmentsAxis=mux_NevadaSubsegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_BlackFoxMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_LexamVgGoldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_LosAzulesCopperProjectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_GoldBarComplexMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_TonkinPropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_ElGalloComplexMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_ElGalloComplexTwoProjectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_NorthBattleMountainComplexLocatedInNevadaUnitedStatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_NorthBattleMountainPropertiesLocatedInNevadaUnitedStatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mux_MineralPropertyNameAxis=mux_GoldBarProjectMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=mux_RoyaltyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=mux_BlackFoxMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mux_ArgentinaReportableSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mux_MexicoReportableSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_PropertyPlantAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsegmentsAxis=mux_NevadaAndArgentinaSubsegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |