Deferred fee plan (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019	Oct. 31, 2019
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Dividends payable		$ 848,000		$ 848,000	$ 1,357,000
Robert S. Hekemian [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	0	54,000	21,000	114,000
Deferred Fee Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense			367,000	471,200
Deferred trustee fees	367,000	517,300	367,000	$ 517,300
Deferred accrued interest	1,091,000		$ 1,091,000		3,188,000
Basis spread on any deferred fee (percentage)			1.50%
Term of distribution to participants			10 years
Shares issued			18,046	32,753
Dividends payable	0	$ 46,100	$ 0	$ 46,100
Cumulative fees			1,542,000		$ 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		$ 4,800,000