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)	(19,888)
Balance at Jun. 30, 2019	40,044	$ 1,334	581,875		(543,165)
Balance (in shares) at Jun. 30, 2019		13,349
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
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)	(914)
Balance at Jun. 30, 2020	17,346	$ 1,334	557,535		(541,523)
Balance (in shares) at Jun. 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