Consolidated Statements Of Changes In Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]		Total
Balance (in shares) at Dec. 31, 2016	23,699,107
Balance at Dec. 31, 2016	$ 2,370	$ 101,738	$ 203,326	$ (1,604)		$ 305,830
Net income			18,214			18,214
Other comprehensive income (loss)				3,110		3,110
Shares withheld upon the vesting and conversion of RSUs (in shares)	(19,339)
Shares withheld upon the vesting and conversion of RSUs	$ (2)	(525)				(527)
Common stock issued under stock compensation plans (in shares)	126,878
Common stock issued under stock compensation plans	$ 13	618				631
Common stock issued under dividend reinvestment and stock purchase plan (in shares)	322,620
Common stock issued under dividend reinvestment and stock purchase plan	$ 32	8,407				8,439
Stock-based compensation		1,331				1,331
Cash dividends declared			(6,753)			(6,753)
Balance (in shares) at Jun. 30, 2017	24,129,266
Balance at Jun. 30, 2017	$ 2,413	111,569	214,787	1,506		330,275
Balance (in shares) at Dec. 31, 2017	24,668,390
Balance at Dec. 31, 2017	$ 2,467	127,122	224,315	546		354,450
Net income			21,426			21,426
Other comprehensive income (loss)				(10,632)		(10,632)
Reclassification of certain stranded tax items upon the adoption of ASU 2018-02			277	(277)	[1]
Shares withheld upon the vesting and conversion of RSUs (in shares)	(25,735)
Shares withheld upon the vesting and conversion of RSUs	$ (3)	(730)				(733)
Common stock issued under stock compensation plans (in shares)	118,900
Common stock issued under stock compensation plans	$ 12	172				184
Common stock issued under dividend reinvestment and stock purchase plan (in shares)	591,781
Common stock issued under dividend reinvestment and stock purchase plan	$ 59	15,795				15,854
Stock-based compensation		1,261				1,261
Cash dividends declared			(7,571)			(7,571)
Balance (in shares) at Jun. 30, 2018	25,353,336
Balance at Jun. 30, 2018	$ 2,535	$ 143,620	$ 238,447	$ (10,363)		$ 374,239

[1] The adoption of Accounting Standards Update ("ASU") 2018-02 "Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income" in the first quarter of 2018 allowed the Corporation to reclassify certain stranded tax effects arising from the enactment of the Tax Cuts and Jobs Act ("Tax Act") in December 2017 from accumulated other comprehensive income to retained earnings. See "Note 11 - Adoption of New Accounting Standards" for more information regarding the effects of adopting ASU 2018-02.