CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss), Net	Total
Balance, beginning at Dec. 31, 2018	$ 50	$ (352)	$ 325,130	$ (316,983)
Balance, beginning (in shares) at Dec. 31, 2018	49,710,104	(33,801)
Increase (Decrease) in Stockholders Equity
Issuance of common stock upon RSU conversion	11,006
Shares issued for exercise of stock options			11
Shares issued for exercise of stock options (in shares)	35,207
Payroll tax withheld for RSU releases			(1)
Share-based compensation expense			874
Net unrealized gain (loss) on investments					$ (1)	$ (1)
Net loss				(7,600)		(7,600)
Balance, ending at Mar. 31, 2019	$ 50	$ (352)	326,014	(324,583)	(1)	1,128
Balance, ending (in shares) at Mar. 31, 2019	49,756,317	(33,801)
Balance, beginning at Dec. 31, 2018	$ 50	$ (352)	325,130	(316,983)
Balance, beginning (in shares) at Dec. 31, 2018	49,710,104	(33,801)
Increase (Decrease) in Stockholders Equity
Issuance of common stock upon RSU conversion	20,328
Shares issued for exercise of stock options (in shares)	36,040
Balance, ending at Dec. 31, 2019	$ 50	$ (352)	328,056	(333,885)	1	$ (6,130)
Balance, ending (in shares) at Dec. 31, 2019	49,766,472	(33,801)				49,766,472
Increase (Decrease) in Stockholders Equity
Issuance of common stock upon RSU conversion	10,451
Shares issued for exercise of stock options (in shares)	833
Payroll tax withheld for RSU releases			(2)
Share-based compensation expense			902
Net loss				(7,950)		$ (7,950)
Balance, ending at Mar. 31, 2020	$ 50	$ (352)	$ 328,956	$ (341,835)	$ 1	$ (13,180)
Balance, ending (in shares) at Mar. 31, 2020	49,777,756	(33,801)				49,777,756