Unaudited Condensed Consolidated Statement of Stockholders' Equity - 9 months ended Dec. 31, 2018 - 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, 2018	$ 44,586	$ 111	$ 278,595	$ (234,120)	$ 0
Beginning 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	$ (135)	$ 1	(136)	0	0
Issuance of common stock under employee and director stock option, RSU, and purchase plans, Shares		554,000
Issuance of common stock from public offering	6,915	$ 5	6,910	0	0
Issuance of common stock from public offering, Shares		5,561,000
Stock-based compensation expense	3,911	$ 0	3,911	0	0
Net loss	(19,652)	0	0	(19,652)	0
Ending balance at Dec. 31, 2018	$ 35,675	$ 118	$ 289,329	$ (253,772)	$ 0
Ending balance, Shares at Dec. 31, 2018		117,770,000