Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Balance at Dec. 31, 2018	$ 58,819	$ 1,334	$ 580,771	$ (9)	$ (523,277)
Balance (in shares) at Dec. 31, 2018		13,343
Stock-based compensation	594		594
Unrealized gain on marketable securities	9			9
Net income (loss)	(10,458)				(10,458)
Balance at Mar. 31, 2019	48,964	$ 1,334	581,365		(533,735)
Balance (in shares) at Mar. 31, 2019		13,343
Balance at Dec. 31, 2018	58,819	$ 1,334	580,771	$ (9)	(523,277)
Balance (in shares) at Dec. 31, 2018		13,343
Unrealized gain on marketable securities	9
Net income (loss)	(20,593)
Balance at Sep. 30, 2019	20,102	$ 1,334	562,638		(543,870)
Balance (in shares) at Sep. 30, 2019		13,363
Balance at Mar. 31, 2019	48,964	$ 1,334	581,365		(533,735)
Balance (in shares) at Mar. 31, 2019		13,343
Stock-based compensation	487		487
Exercise of stock options	23		23
Exercise of stock options (in shares)		6
Net income (loss)	(9,430)				(9,430)
Balance at Jun. 30, 2019	40,044	$ 1,334	581,875		(543,165)
Balance (in shares) at Jun. 30, 2019		13,349
Stock-based compensation	703		703
Exercise of stock options	60		60
Exercise of stock options (in shares)		14
Dividend paid	(20,000)		(20,000)
Net income (loss)	(705)				(705)
Balance at Sep. 30, 2019	20,102	$ 1,334	562,638		(543,870)
Balance (in shares) at Sep. 30, 2019		13,363
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