Represents the amount of amortization expense related to the capitalized asset retirement costs.

No definition available.

Name:	mux_AssetRetirementObligationsAmortization
Namespace Prefix:	mux_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

- 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

- Details

Name:	mux_MineralPropertyInterestsLineItems
Namespace Prefix:	mux_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of properties of the entity which are subject to reclamation obligations.

+ References

No definition available.

+ Details

Name:	mux_NumberOfPropertiesSubjectToReclamationObligations
Namespace Prefix:	mux_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the percentage of annual fees on the value of the surety bonds.

+ References

No definition available.

+ Details

Name:	mux_SuretyBondsAnnualFeesPercentage
Namespace Prefix:	mux_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of upfront deposit on the value of the surety bonds.

+ References

No definition available.

+ Details

Name:	mux_SuretyBondsUpfrontDepositPercentage
Namespace Prefix:	mux_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Current portion of reclamation reserve to restore a mining or drilling site to the condition agreed upon within the mining or drilling contract.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.20)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6911-107765

+ Details

Name:	us-gaap_AccruedReclamationCostsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: 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=8077374&loc=d3e2420-110228

+ Details

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

- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Asset Retirement Obligation

-URI http://asc.fasb.org/extlink&oid=6505190

+ Details

Name:	us-gaap_AssetRetirementObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

+ Details

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

- Definition

Current portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

+ Details

Name:	us-gaap_AssetRetirementObligationCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset.

+ References

+ Details

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

- Definition

Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

+ References

+ Details

Name:	us-gaap_AssetRetirementObligationRevisionOfEstimate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_AssetRetirementObligationRollForwardAnalysisRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The net cash inflow or outflow for the increase (decrease) associated with funds that are not available for withdrawal or use (such as funds held in escrow) and are associated with underlying transactions that are classified as investing activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

Name:	us-gaap_IncreaseDecreaseInRestrictedCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The noncurrent cash, cash equivalents and investments that is restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits classified as long-term; that is not expected to be released from such existing restrictions within one year of the balance sheet date or operating cycle, whichever is longer. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Includes noncurrent cash equivalents and investments that are similarly restricted as to withdrawal, usage or disposal.

+ References

No definition available.

+ Details

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

MINERAL PROPERTY INTERSTS AND ASSET RETIREMENT OBLIGATIONS (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended	9 Months Ended				3 Months Ended	9 Months Ended					3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Argentina	Sep. 30, 2013 Argentina	Sep. 30, 2014 Tonkin property and El Gallo 1 mine portion of the El Gallo Complex item	Sep. 30, 2014 Tonkin Complex	Sep. 30, 2014 El Gallo mine	Sep. 30, 2014 El Gallo mine	Sep. 30, 2013 Telken Tenements Argentina	Sep. 30, 2013 Este Tenements Argentina	Sep. 30, 2013 Piramides Tenements Argentina	Sep. 30, 2013 Tobias Tenements Argentina	Sep. 30, 2013 West Battle Mountain Complex Nevada	Sep. 30, 2013 West Battle Mountain Complex Nevada	Sep. 30, 2013 Exploration properties in Santa Cruz, Argentina Nevada	Sep. 30, 2013 Exploration properties in Santa Cruz, Argentina Nevada	Sep. 30, 2013 Exploration properties located in Santa Cruz, Nevada	Sep. 30, 2013 Exploration properties located in Santa Cruz, Nevada	Jun. 30, 2014 Los Azules Copper Project	Sep. 30, 2014 Los Azules Copper Project	Sep. 30, 2014 Los Azules Copper Project Argentina
Mineral Property Interests [Line Items]
Number of most significant properties subject to reclamation obligations								2
Undiscounted estimated reclamation costs									$ 2,700,000	$ 4,600,000	$ 4,600,000
Cash bonding for mineral properties in the United States	2,000		2,000		5,183,000
Reduction in cash bonding requirements			(5,181,000)
Percentage of annual fees on surety bonds			1.50%
Percentage of upfront deposit on surety bonds			10.00%
Amortization of mineral property interests and asset retirement obligations			923,000	1,244,000						300,000	1,000,000
Amortization of capitalized asset retirement costs										100,000	400,000
Impairment charges		6,287,000	120,398,000	34,016,000		120,398,000	27,729,000					13,792,000	2,784,000	5,079,000	6,074,000	6,287,000	6,287,000	6,300,000	6,300,000	27,700,000	27,700,000	120,400,000		120,398,000
Recovery of deferred income tax	22,500,000	2,200,000	22,500,000	7,000,000														2,200,000	2,200,000	2,300,000	2,300,000		22,500,000
Changes in the asset retirement obligations
Asset retirement obligation liability, beginning balance			7,247,000	6,359,000	6,359,000
Settlements			(43,000)		(60,000)
Accretion of liability	100,000	113,000	309,000	347,000	461,000
Adjustment reflecting updated estimates			(79,000)		487,000
Asset retirement obligation liability, ending balance	7,434,000		7,434,000		7,247,000
Current portion of the asset retirement obligation	$ 1,458,000		$ 1,458,000		$ 1,392,000