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, 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