Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Mar. 31, 2014	$ 48,284	$ 78	$ 140,419	$ (92,213)	$ 0
Beginning balance, Shares at Mar. 31, 2014		78,113,000
Issuance of common stock from warrant exercises, net	$ 445	$ 0	445	0	0
Issuance of common stock from warrant exercises, net, Shares	210,600	211,000
Restricted stock forfeitures	$ 0	$ 0	0	0	0
Restricted stock forfeitures, Shares		(190,000)
Issuance of common stock from public offering, net	22,307	$ 4	22,303	0	0
Issuance of common stock from public offering, Shares		3,198,000
Stock-based compensation expense	7,020	$ 0	7,020	0	0
Warrant liability removed due to exercises of warrants	55	0	55	0	0
Stock option exercises	$ 351	$ 0	351	0	0
Stock option exercises, Shares	205,684	205,000
Issuance of warrants to consultant	$ 316	$ 0	316	0	0
Net loss	(30,082)	0	0	(30,082)	0
Foreign currency translation adjustment	0
Ending balance at Mar. 31, 2015	48,696	$ 82	170,909	(122,295)	0
Ending balance, Shares at Mar. 31, 2015		81,537,000
Issuance of common stock from warrant exercises, net	$ 0	$ 0	0	0	0
Issuance of common stock from warrant exercises, net, Shares	32,914	32,000
Restricted stock forfeitures	$ 0	$ 0	0	0	0
Restricted stock forfeitures, Shares		(132,000)
Issuance of common stock from public offering, net	43,137	$ 10	43,127	0	0
Issuance of common stock from public offering, Shares		10,839,000
Stock-based compensation expense	8,556	$ 0	8,556	0	0
Warrant liability removed due to exercises of warrants	139	0	139	0	0
Stock option exercises	$ 320	$ 0	320	0	0
Stock option exercises, Shares	116,001	116,000
Issuance of warrants to consultant	$ 38	$ 0	38	0	0
Adjustment related to potential equity bonus issuance	(130)	0	(130)	0	0
Net loss	(38,575)	0	0	(38,575)	0
Foreign currency translation adjustment	0
Ending balance at Mar. 31, 2016	62,181	$ 92	222,959	(160,870)	0
Ending balance, Shares at Mar. 31, 2016		92,392,000
Issuance of common stock from warrant exercises, net	$ 336	$ 1	335	0	0
Issuance of common stock from warrant exercises, net, Shares	700,379	700,000
Issuance of common stock under employee and director stock option, RSU and purchase plans	$ 705	$ 0	705	0	0
Issuance of common stock under employee and director stock option, RSU and purchase plans, Shares		397,000
Issuance of common stock from public offering, net	30,206	$ 11	30,195	0	0
Issuance of common stock from public offering, Shares		11,062,000
Stock-based compensation expense	$ 7,392	$ 0	7,392	0	0
Stock option exercises, Shares	245,271
Net loss	$ (38,447)	0	0	(38,447)
Foreign currency translation adjustment	(11)	0	0	0	(11)
Ending balance at Mar. 31, 2017	$ 62,362	$ 104	$ 261,586	$ (199,317)	$ (11)
Ending balance, Shares at Mar. 31, 2017		104,551,000