NATURE OF BUSINESS AND ORGANIZATION (Details) - USD ($)		3 Months Ended		9 Months Ended
	Oct. 11, 2018	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Royalty income		$ 13,891,273	$ 10,898,615	$ 39,663,012	$ 29,889,218
Interest		82,570	26,384	146,830	40,199
Total revenues		13,973,843	10,924,999	39,809,842	29,929,417
Expenses		388,781	227,330	1,037,477	762,869
Net income		$ 13,585,062	$ 10,697,669	$ 38,772,365	$ 29,166,548
Number of units outstanding		13,120,010	13,120,010	13,120,010	13,120,010
Net income per unit (Note 2) (in dollars per unit)		$ 1.0354	$ 0.8154	$ 2.9552	$ 2.2231
Distributions declared per unit (Note 3) (in dollars per unit)	$ 0.94	$ 0.9400	$ 0.6400	$ 1.6100	$ 1.3500
Restatement Adjustment | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Royalty income			$ (1,266,576)		$ 726,461
Total revenues			(1,266,576)		726,461
Net income			$ (1,266,576)		$ 726,461
Net income per unit (Note 2) (in dollars per unit)			$ (0.0965)		$ 0.0554
As Previously Reported | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Royalty income			$ 12,165,191		$ 29,162,757
Interest			26,384		40,199
Total revenues			12,191,575		29,202,956
Expenses			227,330		762,869
Net income			$ 11,964,245		$ 28,440,087
Number of units outstanding			13,120,010		13,120,010
Net income per unit (Note 2) (in dollars per unit)			$ 0.9119		$ 2.1677
Distributions declared per unit (Note 3) (in dollars per unit)			$ 0.6400		$ 1.3500