Deferred fee plan (Details) - USD ($)	9 Months Ended		12 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Oct. 31, 2020
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Dividends payable	$ 343,000
Deferred Fee Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	356,000	444,400
Deferred trustee fees	332,000	$ 444,400
Deferred accrued interest	$ 1,021,000		1,091,000
Basis spread on any deferred fee (percentage)	1.50%
Term of distribution to participants	10 years
Shares issued	20,328	23,302
Dividends payable	$ 24,000	$ 0
Cumulative fees	$ 1,454,000		$ 1,542,000