Consolidated Statements of Stockholders Equity (unaudited) - USD ($) $ in Thousands	Common Stock	Surplus	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2017	$ 197	$ 347,691	$ 96,547	$ (296)	$ (14,939)	$ 429,200
Increase (Decrease) in Stockholders' Equity
Net income			18,816			18,816
Shares issued under the dividend reinvestment plan		468				468
Stock awards granted and distributed	1	(523)		522
Stock awards forfeited		115		(115)
Repurchase of surrendered stock from vesting of stock plans				(552)		(552)
Share based compensation expense		1,787				1,787
Cash dividend declared			(9,157)			(9,157)
Other comprehensive income (loss), net of deferred income taxes					(807)	(807)
Balance at Jun. 30, 2018	198	349,538	106,206	(441)	(15,746)	439,755
Balance at Mar. 31, 2018	198	348,420	104,050	(436)	(18,909)	433,323
Increase (Decrease) in Stockholders' Equity
Net income			6,743			6,743
Shares issued under the dividend reinvestment plan		236				236
Stock awards granted and distributed		(216)		216
Stock awards forfeited		95		(95)
Repurchase of surrendered stock from vesting of stock plans				(126)		(126)
Share based compensation expense		1,003				1,003
Cash dividend declared			(4,587)			(4,587)
Other comprehensive income (loss), net of deferred income taxes					3,163	3,163
Balance at Jun. 30, 2018	198	349,538	106,206	(441)	(15,746)	439,755
Balance at Dec. 31, 2018	198	352,093	117,432	(781)	(15,112)	453,830
Increase (Decrease) in Stockholders' Equity
Net income			23,580			23,580
Shares issued under the dividend reinvestment plan		419				419
Purchase of treasury stock				(321)		(321)
Stock awards granted and distributed	1	(955)		954
Stock awards forfeited		342		(342)
Repurchase of surrendered stock from vesting of stock plans		(18)		(847)		(865)
Share based compensation expense		1,848				1,848
Cash dividend declared			(9,201)			(9,201)
Other comprehensive income (loss), net of deferred income taxes					5,915	5,915
Balance at Jun. 30, 2019	199	353,729	131,811	(1,337)	(9,197)	475,205
Balance at Mar. 31, 2019	199	352,454	125,765	(786)	(12,629)	465,003
Increase (Decrease) in Stockholders' Equity
Net income			10,653			10,653
Shares issued under the dividend reinvestment plan		221				221
Purchase of treasury stock				(321)		(321)
Stock awards granted and distributed		(164)		164
Stock awards forfeited		342		(342)
Repurchase of surrendered stock from vesting of stock plans		(18)		(52)		(70)
Share based compensation expense		894				894
Cash dividend declared			(4,607)			(4,607)
Other comprehensive income (loss), net of deferred income taxes					3,432	3,432
Balance at Jun. 30, 2019	$ 199	$ 353,729	$ 131,811	$ (1,337)	$ (9,197)	$ 475,205