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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)
 12 Months Ended
Jan. 31, 2015
T
Jan. 31, 2014
Cash and Cash Equivalents    
Amount held by the Trust in a money market fund $ 8,717,943us-gaap_MoneyMarketFundsAtCarryingValue $ 7,719,963us-gaap_MoneyMarketFundsAtCarryingValue
Revenue Recognition    
Quantity of iron ore shipped by NMC subject to price determination recognized in revenue (in tons) 702,400msb_RecognizedRevenueSoldQuantitySubjectToPriceDetermination  
Fixed Property, Including Intangibles    
Percentage of fee interest owned by Mesabi Land Trust in the lands subject to the Peters Lease 20.00%msb_PercentageOfFeeInterestHeldByLandTrustInLeaseProperty