Nature of the Business and Operations and Liquidity - Additional Information (Detail) $ in Thousands								1 Months Ended		3 Months Ended		75 Months Ended
	May 06, 2019	Jul. 24, 2018 USD ($)	Jul. 04, 2018 USD ($)	Jul. 03, 2018 USD ($) installment	Mar. 28, 2018 USD ($)	Feb. 01, 2018 USD ($)	May 10, 2017 USD ($)	May 26, 2017 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2018 USD ($) employee	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) employee	Mar. 31, 2018 USD ($)
Description Of Business [Line Items]
Retained earnings (accumulated deficit)										$ (993,037)		$ (993,037)	$ (988,333)
Cash and cash equivalents										26,750		$ 26,750	34,084
Net cash used in operating activities										$ (6,886)	$ (5,430)
Number of workforce persons | employee										231		231
Cash flows from financing activities												$ 85,000
Proceeds from additional equity offering							$ 17,000	$ 17,000
Note receivable										$ 2,720		$ 2,720	$ 2,559
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
Note receivable					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%
Inox Wind Limited
Description Of Business [Line Items]
Strategic agreements value									$ 210,000
Manufacturing agreement period, additional period required									3 years
Subsequent Event | Sinovel Wind Group Co. Ltd.
Description Of Business [Line Items]
Litigation settlement, amount awarded from other party				$ 57,500
Proceeds from settlement			$ 32,500
Number of installments | installment				2
Settlement, amount awarded			$ 25,000
Forecast | Sinovel Wind Group Co. Ltd.
Description Of Business [Line Items]
Payment period	10 months
AMSC Austria | Subsequent Event
Description Of Business [Line Items]
Amount due to subsidiary		$ 30,700