Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2020	$ 16,006	$ 1,334	$ 558,309	$ (543,637)
Balance (in shares) at Dec. 31, 2020		13,380
Exercise of stock options	239		239
Exercise of stock options (in shares)		30
Stock-based compensation	208		208
Net loss	(696)			(696)
Balance at Mar. 31, 2021	15,757	$ 1,334	558,756	(544,333)
Balance (in shares) at Mar. 31, 2021		13,410
Balance at Dec. 31, 2021	14,187	$ 1,334	558,945	(546,092)
Balance (in shares) at Dec. 31, 2021		13,410
Stock-based compensation	20		20
Net loss	(132)			(132)
Balance at Mar. 31, 2022	$ 14,075	$ 1,334	$ 558,965	$ (546,224)
Balance (in shares) at Mar. 31, 2022		13,410