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, 2017	$ 62,362	$ 104	$ 261,586	$ (199,317)	$ (11)
Beginning balance, Shares at Mar. 31, 2017		104,551,000
Stock option exercises	$ 826	$ 1	825	0	0
Stock option exercises, Shares	500,000	500,000
Issuance of common stock under employee and director stock option, RSU and purchase plans	$ 114	$ 1	113	0	0
Issuance of common stock under employee and director stock option, RSU and purchase plans, Shares		675,000
Stock-based compensation expense	6,903	$ 0	6,903	0	0
Issuance of common stock from public offering, net	9,173	$ 5	9,168	0	0
Issuance of common stock from public offering, Shares		5,307,000
Net loss	(34,803)	$ 0	0	(34,803)	0
Currency Translation Adjustment	11	0	0	0	11
Ending balance at Mar. 31, 2018	44,586	$ 111	278,595	(234,120)	0
Ending balance, Shares at Mar. 31, 2018		111,033,000
Stock option exercises	$ 50	$ 1	49	0	0
Stock option exercises, Shares	622,192	622,000
Issuance of common stock under employee and director stock option, RSU and purchase plans	$ (139)	$ 1	(140)	0	0
Issuance of common stock under employee and director stock option, RSU and purchase plans, Shares		728,000
Stock-based compensation expense	5,193	$ 0	5,193	0	0
Issuance of common stock from public offering, net	13,243	$ 11	13,232	0	0
Issuance of common stock from public offering, Shares		11,632,000
Net loss	(26,635)	$ 0	0	(26,635)	0
Currency Translation Adjustment	0
Ending balance at Mar. 31, 2019	$ 36,298	$ 124	$ 296,929	$ (260,755)	$ 0
Ending balance, Shares at Mar. 31, 2019		124,015,000