Stock option plan (Details) - Employee Stock Option [Member] - USD ($)		3 Months Ended
	Sep. 04, 2014	Jan. 31, 2016	Jan. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Plan term	10 years
Vesting term	5 years
No. of Options Outstanding
Options outstanding beginning of period		243,900
Options granted during period	246,000
Options forfeited/cancelled during the period		(500)
Options outstanding end of period		243,400
Options expected to vest		238,620
Options exercisable at end of period		48,680
Exercise Price
Options outstanding beginning of period		$ 18.45
Options granted during period	$ 18.45
Options forfeited/cancelled during period		$ 18.45
Options outstanding end of period		$ 18.45
Such value was estimated on the grant date using a binomial lattice option pricing model using the following assumptions:
Compensation expense related to stock options		$ 24,000	$ 23,000
Unrecognized compensation cost		$ 337,000