Stock option plan (Schedule of Stock Option Activity) (Details) - Employee Stock Option [Member] - USD ($)				3 Months Ended
	May 03, 2018	Nov. 10, 2016	Sep. 04, 2014	Jan. 31, 2019
No. of Options Outstanding
Options outstanding beginning of period				$ 305,780
Options granted during period	38,000	38,000	246,000
Options forfeited/cancelled during period				(40)
Options outstanding end of period				305,740
Options vested and expected to vest				299,140
Options exercisable at end of period				200,260
Weighted Average Exercise Price
Options outstanding beginning of period				$ 18.40
Options granted during period	$ 15.50	$ 21.00	$ 18.45
Options forfeited/cancelled during period				18.45
Options outstanding end of period				$ 18.40