Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Beginning balance at Dec. 31, 2020	$ 191	$ 302,842	$ (277,540)	$ 25,493
Beginning balance, shares at Dec. 31, 2020	19,114
Share-based awards and options exercises	$ 11	1,581		1,592
Share-based awards and options exercises, shares	1,076
Issuance of common stock	$ 56	80,515		80,571
Issuance of common stock (in shares)	5,566
Share-based compensation expense		2,196		2,196
Net loss			(7,881)	(7,881)
Ending balance at Mar. 31, 2021	$ 258	387,134	(285,421)	101,971
Ending balance, shares at Mar. 31, 2021	25,756
Beginning balance at Dec. 31, 2021	$ 264	393,644	(308,733)	85,175
Beginning balance, shares at Dec. 31, 2021	26,395
Share-based awards and options exercises	$ 3	6		9
Share-based awards and options exercises, shares	322
Share-based compensation expense		2,252		2,252
Net loss			(10,838)	(10,838)
Ending balance at Mar. 31, 2022	$ 267	$ 395,902	$ (319,571)	$ 76,598
Ending balance, shares at Mar. 31, 2022	26,717