Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at Dec. 31, 2017	$ 33,547	$ 1,567	$ 302,965	$ (270,285)	$ (700)
Balance, shares at Dec. 31, 2017		156,675,000
Common stock issued under equity compensation plan, net of shares withheld for taxes	(130)	$ 1	(131)
Common stock issued under equity compensation plan, net of shares withheld for taxes, shares		114,000
Exercise of options	28		28
Exercise of options, shares		32,000
Share-based compensation	985		985
Net loss	(6,193)			(6,193)
Other comprehensive income (loss)	10				10
Balance at Mar. 31, 2018	28,247	$ 1,568	303,847	(276,478)	(690)
Balance, shares at Mar. 31, 2018		156,821,000
Balance at Dec. 31, 2018	39,001	$ 1,597	314,907	(276,800)	(703)
Balance, shares at Dec. 31, 2018		159,721,000
Issuance of common stock	7,785	$ 23	7,762
Issuance of common stock, shares		2,307,000
Common stock issued under equity compensation plan, net of shares withheld for taxes	(408)	$ 3	(411)
Common stock issued under equity compensation plan, net of shares withheld for taxes, shares		288,000
Exercise of options	350	$ 2	348
Exercise of options, shares		212,000
Share-based compensation	1,366		1,366
Cumulative effect of change in accounting principle	116			116
Net loss	(5,539)			(5,539)
Other comprehensive income (loss)	(3)				(3)
Balance at Mar. 31, 2019	$ 42,668	$ 1,625	$ 323,972	$ (282,223)	$ (706)
Balance, shares at Mar. 31, 2019		162,528,000