SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue, fixed assets (Details)
|
3 Months Ended |
|
|
Apr. 30, 2019
USD ($)
item
MT
|
Apr. 30, 2018
USD ($)
|
Jan. 31, 2019
USD ($)
|
| Revenue from Contract with Customer [Abstract] |
|
|
|
| Royalty Revenue |
$ 5,361,790
|
$ 6,646,670
|
|
| 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 |
$ 3,377,580
|
|
$ 2,339,060
|
| Contract asset |
1,294,804
|
|
$ 56,357
|
| Base Overriding Royalties |
|
|
|
| Revenue from Contract with Customer [Abstract] |
|
|
|
| Royalty Revenue |
3,068,019
|
3,857,485
|
|
| Bonus Royalties |
|
|
|
| Revenue from Contract with Customer [Abstract] |
|
|
|
| Royalty Revenue |
2,106,957
|
2,634,231
|
|
| Fee Royalties |
|
|
|
| Revenue from Contract with Customer [Abstract] |
|
|
|
| Royalty Revenue |
$ 186,814
|
$ 154,954
|
|