CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Beginning balance at Dec. 31, 2014	$ 230	$ 281,248	$ 52,812	$ (6,794)	$ 1,757	$ 329,253
Beginning balance, shares at Dec. 31, 2014	22,971,504			(437,574)
Purchase of shares of treasury stock				$ (4,418)		$ (4,418)
Purchase of shares of treasury stock, shares				(246,708)		(246,708)
Issuance of shares of treasury stock by exercise of stock options		(97)		$ 257		$ 160
Issuance of shares of treasury stock by exercise of stock options, shares				16,252
Stock-based compensation expense		12				12
Dividends on common stock			(4,487)			(4,487)
Net income			24,136			24,136
Other comprehensive loss, net of tax					(343)	(343)
Ending balance at Dec. 31, 2015	$ 230	281,163	72,461	$ (10,955)	1,414	344,313
Ending balance, shares at Dec. 31, 2015	22,971,504			(668,030)
Purchase of shares of treasury stock				$ (11,079)		$ (11,079)
Purchase of shares of treasury stock, shares				(635,100)		(635,100)
Issuance of shares of treasury stock by exercise of stock options		(2,705)		$ 6,588		$ 3,883
Issuance of shares of treasury stock by exercise of stock options, shares				393,698
Stock-based compensation expense		43				43
Dividends on common stock			(4,395)			(4,395)
Net income			27,208			27,208
Other comprehensive loss, net of tax					(2,336)	(2,336)
Ending balance at Dec. 31, 2016	$ 230	278,501	95,274	$ (15,446)	(922)	357,637
Ending balance, shares at Dec. 31, 2016	22,971,504			(909,432)
Sale of common stock in initial public offering	$ 27	64,492				$ 64,519
Sale of common stock in initial public offering, shares	2,760,000
Purchase of shares of treasury stock, shares						0
Issuance of shares of treasury stock by exercise of stock options		(73)		$ 190		$ 117
Issuance of shares of treasury stock by exercise of stock options, shares				11,160
Stock-based compensation expense		329				329
Dividends on common stock			(4,561)			(4,561)
Net income			27,571			27,571
Other comprehensive loss, net of tax						533
Other comprehensive income, net of tax			69		533	602
Ending balance at Dec. 31, 2017	$ 257	$ 343,249	$ 118,353	$ (15,256)	$ (389)	$ 446,214
Ending balance, shares at Dec. 31, 2017	25,731,504			(898,272)