Nature of the Business and Operations and Liquidity - Additional Information (Detail) $ in Thousands				1 Months Ended	12 Months Ended			60 Months Ended
	May 10, 2017 USD ($)	Apr. 04, 2017	Mar. 24, 2015	Dec. 31, 2015 USD ($)	Mar. 31, 2017 USD ($) employee	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Mar. 31, 2017 USD ($) employee	Mar. 31, 2014 USD ($)
Description Of Business [Line Items]
Reverse stock split			0.1
Accumulated deficit					$ (955,557)	$ (928,184)		$ (955,557)
Cash and cash equivalents					26,784	39,330	$ 20,490	$ 26,784	$ 43,114
Net cash used in operating activities					$ 11,215	4,559	32,676
Number of workforce persons | employee					354			354
Cash flows from financing activities					$ (1,130)	18,202	8,783	$ 69,900
Proceeds from ATM sales, net					2,527	$ 0	$ 5,839
Minimum
Description Of Business [Line Items]
Expected severance cost					1,500			1,500
Maximum
Description Of Business [Line Items]
Expected severance cost					$ 2,000			$ 2,000
Inox Wind Limited
Description Of Business [Line Items]
Strategic agreements value				$ 210,000
Supply commitment, extension period				3 years
Inox Wind Limited | Minimum
Description Of Business [Line Items]
Supply commitment, period				3 years
Inox Wind Limited | Maximum
Description Of Business [Line Items]
Supply commitment, period				4 years
Subsequent event
Description Of Business [Line Items]
Number of positions eliminated, period percent		8.00%
Common Stock | Subsequent event
Description Of Business [Line Items]
Proceeds from additional equity offering	$ 14,700