Nature of Business and Basis of Presentation - Additional Information (Details)	3 Months Ended		9 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
POSCO Energy [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Common stock ownership percentage	2.80%		2.80%
Significant customer revenue percentage	10.00%	13.00%	6.00%	9.00%
NRG Energy, Inc. [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Common stock ownership percentage	1.50%		1.50%
Significant customer revenue percentage	20.00%	0.60%	18.00%	0.40%