Nature of the Business and Operations and Liquidity - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	9 Months Ended							3 Months Ended
	Jul. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2013	Mar. 31, 2012	Apr. 04, 2012 Senior Convertible Debt	Jun. 05, 2012 Senior Secured Term Loan	Nov. 15, 2013 New Term Loan	Dec. 31, 2013 MLV & Co. LLC ATM Arrangement	Nov. 15, 2013 MLV & Co. LLC ATM Arrangement
Description Of Business [Line Items]
Accumulated deficit		$ (833,684,000)	$ (833,684,000)		$ (800,131,000)
Cash and cash equivalents		35,394,000	35,394,000	42,457,000	39,243,000	46,279,000
Net cash used in operating activities			(18,366,000)	(40,691,000)
Debt, face amount							25,000,000	10,000,000	10,000,000
Reduction in global workforce, percentage	7.00%
Restructuring charge for severance and other costs		100,000	900,000
Interest rate percentage							7.00%
Common stock		673,000	673,000		603,000						30,000,000
Net proceeds from sale of common stock										3,300,000
Reduction of principle from conversion of shares			$ 14,600,000