Deferred fee plan (Details) - USD ($)	9 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Oct. 31, 2015
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	$ 574,000
Dividends payable	2,018,000	$ 2,018,000	$ 2,018,000
Deferred Fee Plan [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	521,500	570,900
Deferred trustee fees	$ 574,600	$ 588,300
Basis spread on any deferred fee (percentage)	1.50%
Term of distribution to participants	10 years
Shares issued	29,473	29,385
Dividends payable	$ 53,100	$ 17,400