CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Surplus [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balance at Dec. 31, 2017	$ 403,678	$ 15,858	$ 283,552	$ (8,988)	$ 114,468	$ (1,212)
Net income	22,717				22,717
Other comprehensive income (loss)	(1,669)					(1,669)
Cumulative adjustment for equity security(ASU 2016-01)					(127)	127
Restricted stock units issued		71	(71)
Restricted stock awards forfeitures		(78)	78
Restricted stock units/awards repurchased on vesting to pay taxes	(1,403)	(33)	(1,370)
Amortization of restricted stock awards/units	2,130		2,130
Cash dividends declared on common stock	(1,798)				(1,798)
Common stock options exercised	102	9	93
Sales of shares (Dividend Reinvestment Program)	12,733	326	12,407
Issuance of shares for Employee Stock Purchase Plan	529	13	516
Issuance of common stock for acquisition		17	(17)
Balance at Jun. 30, 2018	437,019	16,183	297,318	(8,988)	135,260	(2,754)
Balance at Mar. 31, 2018	422,406	16,111	293,830	(8,988)	124,295	(2,842)
Net income	11,910				11,910
Other comprehensive income (loss)	88					88
Restricted stock units issued		1	(1)
Restricted stock awards forfeitures		(1)	1
Restricted stock units/awards repurchased on vesting to pay taxes	(66)	(1)	(65)
Amortization of restricted stock awards/units	1,154		1,154
Cash dividends declared on common stock	(945)				(945)
Common stock options exercised	50	4	46
Sales of shares (Dividend Reinvestment Program)	2,114	62	2,052
Issuance of shares for Employee Stock Purchase Plan	308	7	301
Balance at Jun. 30, 2018	437,019	16,183	297,318	(8,988)	135,260	(2,754)
Balance at Dec. 31, 2018	469,013	16,459	309,088	(8,988)	154,799	(2,345)
Net income	22,975				22,975
Other comprehensive income (loss)	741					741
Cumulative adjustment for leases (ASC 842)	661				661
Restricted stock units issued		109	(109)
Restricted stock units/awards repurchased on vesting to pay taxes	(981)	(30)	(951)
Amortization of restricted stock awards/units	2,865		2,865
Cash dividends declared on common stock	(1,940)				(1,940)
Common stock options exercised	22	1	21
Exercise of warrants		2	(2)
Issuance of shares for Employee Stock Purchase Plan	532	15	517
Issuance of common stock for acquisition		1	(1)
Balance at Jun. 30, 2019	493,888	16,557	311,428	(8,988)	176,495	(1,604)
Balance at Mar. 31, 2019	481,472	16,549	309,722	(8,988)	165,918	(1,729)
Net income	11,550				11,550
Other comprehensive income (loss)	125					125
Restricted stock units issued		1	(1)
Restricted stock units/awards repurchased on vesting to pay taxes	(17)		(17)
Amortization of restricted stock awards/units	1,475		1,475
Cash dividends declared on common stock	(973)				(973)
Common stock options exercised	18		18
Issuance of shares for Employee Stock Purchase Plan	238	7	231
Balance at Jun. 30, 2019	$ 493,888	$ 16,557	$ 311,428	$ (8,988)	$ 176,495	$ (1,604)