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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)
3 Months Ended 6 Months Ended
Jul. 31, 2018
USD ($)
shares
Jul. 31, 2017
USD ($)
Jul. 31, 2018
USD ($)
item
MT
shares
Jul. 31, 2017
USD ($)
Jan. 31, 2018
USD ($)
shares
Disaggregation of Revenue [Line Items]          
Beneficial interest in the Trust (in units) | shares 13,120,010   13,120,010   13,120,010
Disaggregation of Revenue [Abstract]          
Royalty Revenue $ 19,125,069 $ 14,230,174 $ 25,771,739 $ 18,990,603  
Base overriding royalties, first tier portion percentage     90.00%    
Base overriding royalties, first tier shipment ceiling (in million tons) | MT     4    
Base overriding royalties, second tier portion percentage     85.00%    
Base overriding royalties, second tier shipment ceiling (in million tons) | MT     2    
Base overriding royalties, third tier portion percentage     25.00%    
Base overriding royalties, third tier shipment threshold (in million tons) | MT     6    
Base overriding royalties, number of volume thresholds for transaction price | item     4    
Base overriding royalties, volume threshold for transaction price | MT     1    
Accrued income receivable 8,776,515   $ 8,776,515   $ 1,956,091
Contract asset 3,006,907   3,006,907   $ 99,264
Base Overriding Royalties          
Disaggregation of Revenue [Abstract]          
Royalty Revenue 11,445,963 7,258,798 15,303,448 9,905,212  
Bonus Royalties          
Disaggregation of Revenue [Abstract]          
Royalty Revenue 7,515,672 6,857,645 10,149,903 8,823,164  
Fee Royalties          
Disaggregation of Revenue [Abstract]          
Royalty Revenue $ 163,434 $ 113,731 $ 318,388 $ 262,227