Deferred fee plan (Details) - USD ($)	6 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Oct. 31, 2015
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Trustee fee expense	$ 392,000
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	359,700	375,000
Deferred trustee fees	$ 392,500	$ 383,000
Basis spread on any deferred fee (percentage)	1.50%
Term of distribution to participants	10 years
Shares issued	20,803	19,371
Dividends payable	$ 32,700	$ 8,600