UNALLOCATED RESERVE AND DISTRIBUTIONS (Details) - USD ($)		3 Months Ended		6 Months Ended
	Jul. 13, 2020	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019	Jan. 31, 2020
Unallocated Cash and Securities portion of Unallocated Reserve
Cash and U.S. Government securities		$ 10,600,605		$ 10,600,605		$ 23,510,129
Distribution payable		(656,001)		(656,001)		(9,184,007)
Unallocated cash and U.S. Government securities		9,944,604		9,944,604		$ 14,326,122
Reconciliation of Trust's Unallocated Reserve
Beginning Balance		6,095,432	$ 10,039,171	11,831,017	$ 16,805,692
Net income		6,676,003	13,911,687	8,287,624	18,821,975
Distributions declared		(656,001)	(2,755,202)	(8,003,207)	(14,432,011)
Ending Balance		$ 12,115,434	$ 21,195,656	$ 12,115,434	$ 21,195,656
Distributions declared per unit (in dollars per unit)	$ 0.05	$ 0.0500	$ 0.2100	$ 0.6100	$ 1.1000
Unallocated Reserve
Reconciliation of Trust's Unallocated Reserve
Beginning Balance		$ 6,095,429	$ 10,039,168	$ 11,831,014	$ 16,805,689
Net income		6,676,003	13,911,687	8,287,624	18,821,975
Distributions declared		(656,001)	(2,755,202)	(8,003,207)	(14,432,011)
Ending Balance		12,115,431	21,195,653	12,115,431	21,195,653
Trust Corpus
Reconciliation of Trust's Unallocated Reserve
Beginning Balance		3	3	3	3
Ending Balance		$ 3	$ 3	$ 3	$ 3