NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details 2) (Gold equivalents, El Gallo mine)	3 Months Ended	6 Months Ended	10 Months Ended	12 Months Ended
Jun. 30, 2013 oz	Jun. 30, 2013 oz	Jun. 30, 2013 oz	Dec. 31, 2012 oz
Gold equivalents \| El Gallo mine
Nature of Operations and Basis of Presentation
Quantity produced (in ounces)	8,561	15,342	22,291	6,949

Represents the quantity of physical commodities produced by the entity during the period.

No definition available.

Name:	mux_ExplorationAndProductionPhysicalCommoditiesQuantityProduced
Namespace Prefix:	mux_
Data Type:	num:massItemType
Balance Type:	na
Period Type:	duration