SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Products, Properties and Production of Minerals (Details) - Gold and Silver - El Gallo 1 mine	12 Months Ended
Dec. 31, 2016
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Option to sell prior to the completion of refining (as a percent)	90.00%
Period of completion of refining	15 days

Represents the option held by the entity to sell the product prior to completion of refining.

No definition available.

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