Concentrations of credit risk - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Jan. 31, 2017	Jan. 31, 2016
Concentration Risk [Line Items]
Cash, FDIC insured amount	$ 3.8
Sales Revenue, Goods, Net
Concentration Risk [Line Items]
Concentration risk, percentage	15.00%	10.00%
Sales Revenue, Goods, Net | Customer One [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%
Sales Revenue, Goods, Net | Customer Two [Member]
Concentration Risk [Line Items]
Concentration risk, percentage		13.00%
Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	17.00%	15.00%
Accounts Receivable | Customer One [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	15.00%
Accounts Receivable | Customer Two [Member]
Concentration Risk [Line Items]
Concentration risk, percentage		13.00%