Description of business.

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Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process.

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Amount awarded from other party in judgment or settlement of litigation.

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Nature of the Business and Operations and Liquidity - Additional Information (Detail) $ in Thousands							1 Months Ended		3 Months Ended		6 Months Ended		78 Months Ended
	May 06, 2019	Jul. 04, 2018 USD ($)	Jul. 03, 2018 USD ($) installment	Mar. 28, 2018 USD ($)	Feb. 01, 2018 USD ($)	May 10, 2017 USD ($)	May 26, 2017 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2018 USD ($) employee	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) employee	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) employee	Mar. 31, 2018 USD ($)
Description Of Business [Line Items]
Retained earnings (accumulated deficit)									$ (970,479)		$ (970,479)		$ (970,479)	$ (988,333)
Cash and cash equivalents									56,169		56,169		$ 56,169	34,084
Net cash used in operating activities											23,595	$ (13,539)
Net Sinovel settlement									$ 28,720	$ 0	$ 28,720	0
Number of workforce persons \| employee									225		225		225
Cash flows from financing activities											$ (325)	$ 15,188	$ 84,900
Proceeds from additional equity offering						$ 17,000	$ 17,000
Notes receivable, long term portion									$ 2,776		$ 2,776		$ 2,776	$ 2,559
Sinovel Wind Group Co. Ltd.
Description Of Business [Line Items]
Net Sinovel settlement									$ 28,700
Sinovel settlement			$ 57,500
Proceeds from settlement		$ 32,500
Number of installments \| installment			2
Settlement, amount awarded		$ 25,000
64 Jackson LLC
Description Of Business [Line Items]
Purchase and sale agreement, total consideration				$ 23,000	$ 23,000
Purchase and sale agreement, sale of property				17,000
Notes receivable, long term portion				6,000	$ 6,000
Purchase and sale agreement, proceeds from sale of property, plant and equipment, net				$ 16,900
Interest rate				1.96%					1.96%		1.96%		1.96%
Inox Wind Limited
Description Of Business [Line Items]
Strategic agreements value								$ 210,000
Manufacturing agreement period, additional period required								3 years
Forecast \| Sinovel Wind Group Co. Ltd.
Description Of Business [Line Items]
Payment period	10 months