UNALLOCATED RESERVE AND DISTRIBUTIONS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014	Jan. 31, 2015
UNALLOCATED RESERVE AND DISTRIBUTIONS
Cash and U.S. Government securities	$ 6,551,542		$ 6,551,542		$ 9,484,275
Distribution payable					(8,396,806)
Unallocated cash and U.S. Government securities	6,551,542		6,551,542		$ 1,087,469
Reconciliation of unallocated reserve
Unallocated Reserve at the beginning of the period			1,611,124
Net income, nine months ended October 31, 2015	2,402,067	$ 11,539,606	5,825,977	$ 19,093,365
Distributions declared			(524,800)
Unallocated Reserve at the end of the period	6,912,301		6,912,301
Minimum
UNALLOCATED RESERVE AND DISTRIBUTIONS
Unallocated cash and U.S. Government securities	500,000		500,000
Maximum
UNALLOCATED RESERVE AND DISTRIBUTIONS
Unallocated cash and U.S. Government securities	$ 1,000,000		$ 1,000,000