CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Total
Balance at Dec. 31, 2019	$ 191	$ 35,215	$ 318,572	$ (12,777)	$ 341,201
Balance (in shares) at Dec. 31, 2019	18,141,383
Increase (Decrease) in Stockholders' Equity
Exercise of stock options, net		(428)		428
Exercise of stock options, net (in shares)	30,545
Stock-based compensation expense		873			873
Net income			2,020		2,020
Balance at Mar. 31, 2020	$ 191	35,660	320,592	(12,349)	344,094
Balance (in shares) at Mar. 31, 2020	18,171,928
Balance at Dec. 31, 2020	$ 191	34,498	342,250	(8,872)	$ 368,067
Balance (in shares) at Dec. 31, 2020	18,426,130				18,426,130
Increase (Decrease) in Stockholders' Equity
Exercise of stock options, net		1,143		1,266	$ 2,409
Exercise of stock options, net (in shares)	91,831
Stock-based compensation expense		1,280			1,280
Net income			8,154		8,154
Balance at Mar. 31, 2021	$ 191	$ 36,921	$ 350,404	$ (7,606)	$ 379,910
Balance (in shares) at Mar. 31, 2021	18,517,961				18,517,961