Sales by geographic area (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Revenue, Major Customer [Line Items]
Sales revenue	$ 7,808	$ 7,640	$ 22,065	$ 22,159
United States
Revenue, Major Customer [Line Items]
Sales revenue	7,603	7,441	21,557	21,536
Canada
Revenue, Major Customer [Line Items]
Sales revenue	180	90	356	236
Israel
Revenue, Major Customer [Line Items]
Sales revenue	0	1	0	63
Mexico
Revenue, Major Customer [Line Items]
Sales revenue	0	85	77	234
All other
Revenue, Major Customer [Line Items]
Sales revenue	25	23	75	90
Foreign countries, total
Revenue, Major Customer [Line Items]
Sales revenue	$ 205	$ 199	$ 508	$ 623