Sales by geographic area (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Revenue, Major Customer [Line Items]
Sales revenue	$ 13,626	$ 20,515	$ 24,273	$ 28,482
United States
Revenue, Major Customer [Line Items]
Sales revenue	13,451	20,376	23,921	28,137
Canada
Revenue, Major Customer [Line Items]
Sales revenue	113	125	278	280
Mexico
Revenue, Major Customer [Line Items]
Sales revenue	0	0	0	39
All Other
Revenue, Major Customer [Line Items]
Sales revenue	62	14	74	26
Foreign Countries, total
Revenue, Major Customer [Line Items]
Sales revenue	$ 175	$ 139	$ 352	$ 345