ASSET RETIREMENT OBLIGATIONS (Details) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Changes in the asset retirement obligations
Outstanding surety bonds	$ 4,800,000mux_OutstandingSuretyBonds		$ 4,800,000mux_OutstandingSuretyBonds
Amortization of mineral property interests and asset retirement obligations	322,000	322,000
Asset retirement obligation liability, beginning balance	7,471,000us-gaap_AssetRetirementObligation	7,247,000us-gaap_AssetRetirementObligation	7,247,000us-gaap_AssetRetirementObligation
Settlements			(52,000)
Accretion of liability	101,000	101,000	407,000
Adjustment reflecting updated estimates			(131,000)
Asset retirement obligation liability, ending balance	7,572,000us-gaap_AssetRetirementObligation		7,471,000us-gaap_AssetRetirementObligation
Current portion of the asset retirement obligation	2,456,000		2,427,000
Tonkin property and El Gallo 1 mine portion of the El Gallo Complex
Changes in the asset retirement obligations
Number of most significant properties subject to reclamation obligations	2
El Gallo mine
Changes in the asset retirement obligations
Amortization of mineral property interests and asset retirement obligations	300,000		300,000
Amortization of capitalized asset retirement costs	$ 100,000		$ 100,000

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

No definition available.

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Namespace Prefix:	mux_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

The value of the outstanding surety bonds.

+ References

No definition available.

+ Details

Name:	mux_OutstandingSuretyBonds
Namespace Prefix:	mux_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

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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

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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

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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

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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

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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

- Details

Name:	mux_MineralPropertyNameAxis=mux_ElGalloComplexMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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