Deferred fee plan (Details) - USD ($)	3 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Oct. 31, 2015
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	$ 182,000
Dividends payable	2,018,000	$ 2,046,000	$ 2,018,000
Deferred Fee Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	167,500	184,000
Deferred trustee fees	$ 182,200	$ 187,000
Basis spread on any deferred fee (percentage)	1.50%
Term of distribution to participants	10 years
Shares issued	10,334	9,807
Dividends payable	$ 14,700	$ 3,000