Royalty Agreement, Unallocated Reserve and Distributions (Details) - USD ($)		3 Months Ended		9 Months Ended
	Oct. 14, 2022	Oct. 31, 2022	Oct. 31, 2021	Oct. 31, 2022	Oct. 31, 2021	Jan. 31, 2022
Unallocated Cash and Securities portion of Unallocated Reserve
Cash and U.S. Government securities		$ 14,504,539		$ 14,504,539		$ 47,727,522
Distribution payable						(22,960,018)
Unallocated cash and U.S. Government securities		14,504,539		14,504,539		$ 24,767,504
Reconciliation of Trust's Unallocated Reserve
Beginning Balance		14,866,946	$ 38,949,339	30,794,752	$ 16,477,049
Net income (loss)		(413,692)	15,992,906	8,324,122	51,322,806
Distributions declared			(18,630,414)	(24,665,620)	(31,488,024)
Ending Balance		$ 14,453,254	$ 36,311,831	$ 14,453,254	$ 36,311,831
Distributions declared per unit (in dollars per unit)	$ 0	$ 0.00	$ 1.4200	$ 1.8800	$ 2.4000
Unallocated Reserve member
Reconciliation of Trust's Unallocated Reserve
Beginning Balance		$ 14,866,943	$ 38,949,336	$ 30,794,749	$ 16,477,046
Net income (loss)		(413,692)	15,992,906	8,324,122	51,322,806
Distributions declared			(18,630,414)	(24,665,620)	(31,488,024)
Ending Balance		14,453,251	36,311,828	14,453,251	36,311,828
Trust Corpus
Reconciliation of Trust's Unallocated Reserve
Beginning Balance		3	3	3	3
Ending Balance		$ 3	$ 3	$ 3	$ 3