Accounts Receivable - Additional Information (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Oct. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Allowance for Doubtful Accounts Receivable, Current	$ 100	$ 200
POSCO Energy [Member]
Accounts Notes And Loans Receivable [Line Items]
Accounts Receivable, Related Parties, Current	2,000	5,000
NRG Energy, Inc. [Member]
Accounts Notes And Loans Receivable [Line Items]
Accounts Receivable, Related Parties, Current	$ 20	$ 100