Stock option plan (Details) - USD ($)			3 Months Ended
	Nov. 10, 2016	Sep. 04, 2014	Jan. 31, 2017	Jan. 31, 2016
Weighted Average Exercise Price
Estimated fair value of options granted			$ 3.54
Employee Stock Option [Member]
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
Options vested and expected to vest			262,280
Options exercisable at end of period			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
Compensation expense related to stock options			$ 31,000	$ 24,000
Unrecognized compensation cost			371,000
Aggregate intrinsic value of options expected to vest			605,000
Aggregate intrinsic value of options exercisable			$ 224,000