NATURE OF BUSINESS AND ORGANIZATION - SCF (Details) - USD ($)	9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Royalties received	$ 34,316,372	$ 24,271,530
Interest received	74,962	39,896
Expenses paid	(1,054,741)	(825,270)
Net cash from operating activities	33,336,593	23,486,156
Maturities of U.S. Government securities	28,893,900	9,933,171
Purchases of U.S. Government securities	(37,767,613)	(35,768,880)
Net cash used for investing activities	(8,773,973)	(25,835,709)
Distributions to unitholders	(24,272,019)	(11,152,009)
Net change in cash and cash equivalents	290,601	(13,501,562)
Cash and cash equivalents, beginning of period	314,835	13,695,168
Cash and cash equivalents, end of period	605,436	193,606
Net income	38,772,365	29,166,548
Increase in accrued income receivable	(4,154,875)	(2,792,115)
Increase in contract asset	(1,263,633)	(726,461)
Increase in prepaid expense	(40,703)	(41,078)
Decrease in accrued expenses	23,439	(21,323)
Decrease in contract liability		(2,099,415)
Distributions declared and payable	12,332,809	8,396,806
Restatement Adjustment | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income		726,461
Increase in contract asset		(726,461)
As Previously Reported | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Royalties received		24,271,530
Interest received		39,896
Expenses paid		(825,270)
Net cash from operating activities		23,486,156
Maturities of U.S. Government securities		9,933,171
Purchases of U.S. Government securities		(35,768,880)
Net cash used for investing activities		(25,835,709)
Distributions to unitholders		(11,152,009)
Net change in cash and cash equivalents		(13,501,562)
Cash and cash equivalents, beginning of period	$ 314,835	13,695,168
Cash and cash equivalents, end of period		193,606
Net income		28,440,087
Increase in accrued income receivable		(2,792,115)
Increase in prepaid expense		(41,078)
Decrease in accrued expenses		(21,323)
Decrease in contract liability		(2,099,415)
Distributions declared and payable		$ 8,396,806