Concentrations of credit risk - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Concentration Risk [Line Items]
Cash, FDIC insured amount	$ 5.2
Sales Revenue, Goods, Net
Concentration Risk [Line Items]
Concentration risk, percentage		15.00%
Sales Revenue, Goods, Net | Customer One [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	20.00%
Sales Revenue, Goods, Net | Customer Two [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	11.00%
Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage		20.00%
Accounts Receivable | Customer One [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	27.00%
Accounts Receivable | Customer Two [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	5.00%