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Concentrations of credit risk - Additional Information (Detail) (USD $)
6 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended 3 Months Ended 6 Months Ended
Apr. 30, 2014
Apr. 30, 2014
Sales Revenue, Goods, Net
Apr. 30, 2013
Sales Revenue, Goods, Net
Apr. 30, 2014
Sales Revenue, Goods, Net
Apr. 30, 2013
Sales Revenue, Goods, Net
Apr. 30, 2014
Accounts Receivable
Oct. 31, 2013
Accounts Receivable
Apr. 30, 2014
Optiflex Customer Concentration Risk
Apr. 30, 2014
Optiflex Customer Concentration Risk
Concentration Risk [Line Items]                  
Cash, FDIC insured amount $ 12,300,000                
Concentration risk, percentage   30.00% 50.00% 33.00% 52.00% 24.00% 27.00% 7.00% 13.00%
Concentration agreement with major customer 15 years                
Sales revenue, goods, net               $ 399,000 $ 1,500,000