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, 2019	$ 17,312	$ 1,334	$ 556,587	$ (540,609)
Balance (in shares) at Dec. 31, 2019		13,380
Stock-based compensation	484		484
Net income (loss)	249			249
Balance at Mar. 31, 2020	18,045	$ 1,334	557,071	(540,360)
Balance (in shares) at Mar. 31, 2020		13,380
Balance at Dec. 31, 2019	17,312	$ 1,334	556,587	(540,609)
Balance (in shares) at Dec. 31, 2019		13,380
Net income (loss)	(1,920)
Balance at Sep. 30, 2020	16,740	$ 1,334	557,935	(542,529)
Balance (in shares) at Sep. 30, 2020		13,380
Balance at Mar. 31, 2020	18,045	$ 1,334	557,071	(540,360)
Balance (in shares) at Mar. 31, 2020		13,380
Stock-based compensation	464		464
Net income (loss)	(1,163)			(1,163)
Balance at Jun. 30, 2020	17,346	$ 1,334	557,535	(541,523)
Balance (in shares) at Jun. 30, 2020		13,380
Stock-based compensation	400		400
Net income (loss)	(1,006)			(1,006)
Balance at Sep. 30, 2020	16,740	$ 1,334	557,935	(542,529)
Balance (in shares) at Sep. 30, 2020		13,380
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 income (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, 2020	16,006	$ 1,334	558,309	(543,637)
Balance (in shares) at Dec. 31, 2020		13,380
Net income (loss)	(1,980)
Balance at Sep. 30, 2021	14,619	$ 1,334	558,902	(545,617)
Balance (in shares) at Sep. 30, 2021		13,410
Balance at Mar. 31, 2021	15,757	$ 1,334	558,756	(544,333)
Balance (in shares) at Mar. 31, 2021		13,410
Stock-based compensation	93		93
Net income (loss)	(759)			(759)
Balance at Jun. 30, 2021	15,091	$ 1,334	558,849	(545,092)
Balance (in shares) at Jun. 30, 2021		13,410
Stock-based compensation	53		53
Net income (loss)	(525)			(525)
Balance at Sep. 30, 2021	$ 14,619	$ 1,334	$ 558,902	$ (545,617)
Balance (in shares) at Sep. 30, 2021		13,410