Stock option plan (Details) - Employee Stock Option [Member] - USD ($)			3 Months Ended		6 Months Ended
	Nov. 10, 2016	Sep. 04, 2014	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Plan term	10 years	10 years
Vesting term	5 years	5 years
No. of Options Outstanding
Options outstanding beginning of period					229,880
Options granted during period	38,000	246,000			38,000
Options forfeited/cancelled during period					(60)
Options outstanding end of period			267,820		267,820
Options vested and expected to vest			262,280		262,280
Options exercisable at end of period			84,080		84,080
Weighted Average Exercise Price
Options outstanding beginning of period					$ 18.45
Options granted during period	$ 21.00	$ 18.45			21.00
Options forfeited/cancelled during period					18.45
Options outstanding end of period			$ 18.81		$ 18.81
Compensation expense related to stock options			$ 30,000	$ 23,000	$ 61,000	$ 47,000
Unrecognized compensation cost			340,000		340,000
Aggregate intrinsic value of options expected to vest			475,000		475,000
Aggregate intrinsic value of options exercisable			$ 177,000		$ 177,000