Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Retained Earnings [Member]
Beginning balance at Dec. 31, 2016	$ 69,693	$ 72	$ 9,638	$ (3)	$ 59,986
Beginning balance, shares at Dec. 31, 2016		7,244
Common stock issued on exercise of options and vesting of restricted stock units	145	$ 1	144
Common stock issued on exercise of options and vesting of restricted stock units, shares		14
Common stock repurchased on vesting of restricted stock units	(134)		(134)
Common stock repurchased on vesting of restricted stock units, shares		(2)
Share-based compensation expense	1,772		1,772
Cash dividends on common stock	(3,625)				(3,625)
Unrealized gain (loss) on investments, net of tax	113			113
Net income (loss)	(101)				(101)
Ending balance at Jun. 30, 2017	67,863	$ 73	11,420	110	56,260
Ending balance, shares at Jun. 30, 2017		7,256
Beginning balance at Dec. 31, 2017	88,834	$ 73	12,311	(1,430)	77,880
Beginning balance, shares at Dec. 31, 2017		7,301
Common stock issued on exercise of options and vesting of restricted stock units	101		101
Common stock issued on exercise of options and vesting of restricted stock units, shares		12
Common stock repurchased on vesting of restricted stock units	(168)		(168)
Common stock repurchased on vesting of restricted stock units, shares		(2)
Share-based compensation expense	2,583		2,583
Cash dividends on common stock	(3,653)				(3,653)
Unrealized gain (loss) on investments, net of tax	(4,939)			(4,939)
Net income (loss)	2,117				2,117
Ending balance at Jun. 30, 2018	$ 84,875	$ 73	$ 14,827	$ (6,369)	$ 76,344
Ending balance, shares at Jun. 30, 2018		7,311