Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2020	$ 198,235	$ 76	$ 24,885	$ 7,564	$ 165,710
Beginning Balance, shares at Dec. 31, 2020		7,566
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards	815		815
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards, shares		38
Common stock repurchased on vesting of restricted stock units and performance awards	(107)		(107)
Common stock repurchased on vesting of restricted stock units and performance awards, shares		(1)
Share-based compensation expense	1,060		1,060
Company repurchase of common stock	(3,436)		(170)		(3,266)
Company repurchase of common stock, shares		(49)
Cash dividends on common stock	(2,278)				(2,278)
Unrealized loss on investments, net of tax	(5,250)			(5,250)
Net income (loss)	(4,554)				(4,554)
Ending Balance at Mar. 31, 2021	184,485	$ 76	26,483	2,314	155,612
Ending Balance, shares at Mar. 31, 2021		7,554
Beginning Balance at Dec. 31, 2021	208,530	$ 74	29,054	1,079	178,323
Beginning Balance, shares at Dec. 31, 2021		7,415
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards	411		411
Common stock issued on exercise of options, purchase of ESPP shares and vesting of restricted stock units and performance awards, shares		18
Common stock repurchased on vesting of restricted stock units and performance awards	(185)		(185)
Common stock repurchased on vesting of restricted stock units and performance awards, shares		(4)
Share-based compensation expense	1,830		1,830
Company repurchase of common stock	(8,575)	$ (1)	(484)		(8,090)
Company repurchase of common stock, shares		(115)
Cash dividends on common stock	(2,229)				(2,229)
Unrealized loss on investments, net of tax	(14,358)			(14,358)
Net income (loss)	288				288
Ending Balance at Mar. 31, 2022	$ 185,712	$ 73	$ 30,626	$ (13,279)	$ 168,292
Ending Balance, shares at Mar. 31, 2022		7,314