Deferred fee plan (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Oct. 31, 2019
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Dividends payable		$ 1,014,000	$ 1,357,000
Robert S. Hekemian [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	21,000	60,000
Deferred Fee Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	203,000	238,200
Deferred trustee fees	203,000	$ 212,600
Deferred accrued interest	$ 1,161,000		3,188,000
Basis spread on any deferred fee (percentage)	1.50%
Term of distribution to participants	10 years
Shares issued	9,230	15,204
Dividends payable	$ 0	$ 25,600
Cumulative fees	1,630,000		$ 4,422,000
Deferred Fee Plan [Member] | Robert S. Hekemian [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Lump sum accrued plan benefits payable related party	$ 4,800,000