Unaudited Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock
Beginning Balance (in shares) at Dec. 31, 2018			17,784,769			4,970,093
Beginning Balance at Dec. 31, 2018		$ 310,998	$ 18	$ 334,744	$ 187,127	$ (210,891)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		2,103		2,103
Exercise of employee stock options (in shares)			57,022			0
Exercise of employee stock options		2,557	$ 0	2,557		$ 0
Restricted stock issued (in shares)			25,357			3,459
Restricted stock issued		(217)				$ (217)
Shares issued for bonus settlement and director stipends (in shares)			599
Shares issued for bonus settlement and director stipends		0		0
Convertible preferred stock dividends	[1]	(1,087)			(1,087)
Net income		582			582
Ending Balance (in shares) at Mar. 31, 2019			17,867,747			4,973,552
Ending Balance at Mar. 31, 2019		314,936	$ 18	339,404	186,622	$ (211,108)
Beginning Balance (in shares) at Dec. 31, 2019			18,073,763			5,088,782
Beginning Balance at Dec. 31, 2019		317,592	$ 18	351,529	183,733	$ (217,688)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		1,005		1,005
Exercise of employee stock options (in shares)			39,111
Exercise of employee stock options		2,054		2,054
Restricted stock issued (in shares)			79,029			626
Restricted stock issued		(37)				$ (37)
Shares issued for bonus settlement and director stipends (in shares)			701
Shares issued for bonus settlement and director stipends		38		38
Stock repurchase (in shares)						142,821
Stock repurchase plan		(7,299)				$ (7,299)
Convertible preferred stock dividends	[2]	$ (1,095)			(1,095)
Conversion of convertible preferred stock to common stock (in shares)		40
Conversion of convertible preferred stock to common stock		$ 2		2
Net income		16,098			16,098
Ending Balance (in shares) at Mar. 31, 2020			18,192,644			5,232,229
Ending Balance at Mar. 31, 2020		$ 328,358	$ 18	$ 354,628	$ 198,736	$ (225,024)

[1] Cash dividends on redeemable convertible preferred stock of $1.36 per share were distributed to convertible preferred stockholders for the three months ended March 31, 2019.

[2] Cash dividends on redeemable convertible preferred stock of $1.37 per share were distributed to convertible preferred stockholders for the three months ended March 31, 2020.