Nature of Business and Basis of Presentation - Additional Information (Details) $ in Thousands		1 Months Ended	3 Months Ended		4 Months Ended	9 Months Ended
		Jun. 30, 2017 MW	Jul. 31, 2017 USD ($)	Jul. 31, 2016	Sep. 30, 2017 Employee	Jul. 31, 2017 USD ($)	Jul. 31, 2016	Oct. 31, 2016 USD ($)
Nature of Business and Basis of Presentation [Line items]
Debt issuance costs, deduction of current portion of long term debt	[1]		$ 129			$ 129		$ 152
Debt issuance costs, deduction of long-term debt and other liabilities	[2]		$ 129			$ 129		225
Reduction in production capacity due to production rate adjustment | MW		15
Scenario, Forecast [Member]
Nature of Business and Basis of Presentation [Line items]
Number of manufacturing employees | Employee					110
POSCO Energy [Member]
Nature of Business and Basis of Presentation [Line items]
Common stock ownership percentage			4.00%			4.00%
Significant customer revenue percentage			13.00%	65.00%		9.00%	52.00%
NRG Energy, Inc. [Member]
Nature of Business and Basis of Presentation [Line items]
Common stock ownership percentage			2.00%			2.00%
Significant customer revenue percentage			0.60%	0.30%		0.40%	0.20%
Accounting Standards Update 2015-03 [Member] | Current Assets [Member]
Nature of Business and Basis of Presentation [Line items]
Debt issuance costs, deduction of current portion of long term debt								300
Accounting Standards Update 2015-03 [Member] | Other Assets [Member]
Nature of Business and Basis of Presentation [Line items]
Debt issuance costs, deduction of long-term debt and other liabilities								$ 1,100

[1] Represents the current portion of direct deferred finance costs that relate primarily to securing a $40.0 million loan facility with NRG which is being amortized over the five-year life of the facility.

[2] Represents the long-term portion of direct deferred finance costs relating to the Company’s loan facility with NRG which is being amortized over the five-year life of the facility.