Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance (shares) at Dec. 31, 2017		48,365,000
Beginning balance at Dec. 31, 2017	$ 24,547	$ 5	$ 340,079	$ (472)	$ (315,065)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)	78,859	79,000
Exercise of stock options	$ 435		435
Release of stock awards (shares)		778,000
Employee stock-based compensation	1,958		1,958
Non-employee stock-based compensation	22		22
Net shares settlements for taxes (shares)		(297,000)
Taxes paid related to net share settlement of equity awards	(3,140)		(3,140)
Net loss	(4,694)				(4,694)
Ending balance (shares) at Mar. 31, 2018		48,925,000
Ending balance at Mar. 31, 2018	15,068	$ 5	339,354	0	(324,291)
Beginning balance (shares) at Dec. 31, 2018		54,065,000
Beginning balance at Dec. 31, 2018	$ 56,306	$ 5	386,775	0	(330,474)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (shares)	218,572	219,000
Exercise of stock options	$ 776		776
Release of stock awards (shares)		402,000
Employee stock-based compensation	2,063		2,063
Net shares settlements for taxes (shares)		(145,000)
Taxes paid related to net share settlement of equity awards	(2,799)		(2,799)
Net loss	(5,136)				(5,136)
Ending balance (shares) at Mar. 31, 2019		54,541,000
Ending balance at Mar. 31, 2019	$ 51,210	$ 5	$ 386,815	$ 0	$ (335,610)