Unaudited Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]
Beginning balance at Mar. 31, 2021	$ 39,196	$ 9	$ 335,479	$ (1)	$ (296,291)
Beginning balance, Shares at Mar. 31, 2021		8,671		0
Issuance of common stock from public offering, net	251	$ 0	251	$ 0	0
Issuance of common stock from public offering, Shares		27
Stock-based compensation expense	415	$ 0	415	0	0
Net loss	(2,532)	0	0	0	(2,532)
Ending balance at Jun. 30, 2021	37,330	$ 9	336,145	$ (1)	(298,823)
Ending balance, Shares at Jun. 30, 2021		8,698		0
Beginning balance at Mar. 31, 2021	39,196	$ 9	335,479	$ (1)	(296,291)
Beginning balance, Shares at Mar. 31, 2021		8,671		0
Net loss	(6,037)
Ending balance at Sep. 30, 2021	34,206	$ 9	336,526	$ (1)	(302,328)
Ending balance, Shares at Sep. 30, 2021		8,705		0
Beginning balance at Jun. 30, 2021	37,330	$ 9	336,145	$ (1)	(298,823)
Beginning balance, Shares at Jun. 30, 2021		8,698		0
Issuance of common stock under employee and director stock option, RSU, and purchase plans	(45)	$ 0	(45)	$ 0	0
Issuance of common stock under employee and director stock option, restricted stock units, and purchase plans, Shares		7
Stock-based compensation expense	426	$ 0	426	0	0
Net loss	(3,505)	0	0	0	(3,505)
Ending balance at Sep. 30, 2021	34,206	$ 9	336,526	$ (1)	(302,328)
Ending balance, Shares at Sep. 30, 2021		8,705		0
Beginning balance at Mar. 31, 2022	30,209	$ 9	337,940	$ (1)	(307,739)
Beginning balance, Shares at Mar. 31, 2022		8,711		0
Issuance of common stock under employee and director stock option, RSU, and purchase plans	0	$ 0	0	$ 0	0
Issuance of common stock under employee and director stock option, restricted stock units, and purchase plans, Shares		1
Stock-based compensation expense	660	$ 0	660	0	0
Net loss	(3,215)	0	0	0	(3,215)
Ending balance at Jun. 30, 2022	27,654	$ 9	338,600	$ (1)	(310,954)
Ending balance, Shares at Jun. 30, 2022		8,712		0
Beginning balance at Mar. 31, 2022	30,209	$ 9	337,940	$ (1)	(307,739)
Beginning balance, Shares at Mar. 31, 2022		8,711		0
Net loss	(6,536)
Ending balance at Sep. 30, 2022	25,006	$ 9	339,273	$ (1)	(314,275)
Ending balance, Shares at Sep. 30, 2022		8,713		0
Beginning balance at Jun. 30, 2022	27,654	$ 9	338,600	$ (1)	(310,954)
Beginning balance, Shares at Jun. 30, 2022		8,712		0
Issuance of common stock under employee and director stock option, RSU, and purchase plans	0	$ 0	0	$ 0	0
Issuance of common stock under employee and director stock option, restricted stock units, and purchase plans, Shares		1
Stock-based compensation expense	673	$ 0	673	0	0
Net loss	(3,321)	0	0	0	(3,321)
Ending balance at Sep. 30, 2022	$ 25,006	$ 9	$ 339,273	$ (1)	$ (314,275)
Ending balance, Shares at Sep. 30, 2022		8,713		0