Condensed Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2017		37,765
Balance at Dec. 31, 2017	$ 23,291	$ 378	$ 232,960	$ (209,013)	$ (1,034)
Net income	8,211			8,211
Forfeiture of dividend equivalent right	355			355
Other comprehensive income	0				0
Stock option exercises and employee stock plan purchases (in shares)		94
Stock option exercises and employee stock plan purchases	720	$ 1	719
Vesting of restricted stock awards and units (in shares)		174
Vesting of restricted stock awards and units	0	$ 2	(2)
Shares withheld to cover taxes (in shares)		(36)
Shares withheld to cover taxes	(709)	$ (1)	(708)
Stock-based compensation	1,796		1,796
Balance (in shares) at Mar. 31, 2018		37,997
Balance at Mar. 31, 2018	33,664	$ 380	234,765	(200,447)	(1,034)
Balance (in shares) at Dec. 31, 2018		38,466
Balance at Dec. 31, 2018	71,002	$ 385	239,865	(168,140)	(1,108)
Net income	9,949			9,949
Other comprehensive income	56				56
Stock option exercises and employee stock plan purchases (in shares)		37
Stock option exercises and employee stock plan purchases	606	$ 0	606
Vesting of restricted stock awards and units (in shares)		365
Vesting of restricted stock awards and units	0	$ 4	(4)
Shares withheld to cover taxes (in shares)		(50)
Shares withheld to cover taxes	(1,120)	$ (1)	(1,119)
Stock-based compensation	2,720		2,720
Balance (in shares) at Mar. 31, 2019		38,818
Balance at Mar. 31, 2019	$ 83,213	$ 388	$ 242,068	$ (158,191)	$ (1,052)