Consolidated Statement 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, 2015	14,116,677
Balance at Dec. 31, 2015	$ 1,412	$ 56,931	$ 185,069	$ 7,524		$ 250,936
Net income			30,880			30,880
Other comprehensive income (loss)				(9,128)		(9,128)
Common stock issued in public offering, net of issuance costs (in shares)	1,300,000
Common stock issued in public offering, net of issuance costs	$ 130	35,140				35,270
Shares withheld upon the vesting and conversion of RSUs (in shares)	(13,393)
Shares withheld upon the vesting and conversion of RSUs	$ (1)	(369)				(370)
Common stock issued under stock compensation plans (in shares)	109,409
Common stock issued under stock compensation plans	$ 11	895				906
Common stock issued under dividend reinvestment and stock purchase plan (in shares)	287,498
Common stock issued under dividend reinvestment and stock purchase plan	$ 28	8,414				8,442
3-for-2 stock split (in shares)	7,898,916
3-for-2 stock split	$ 790	(790)
Stock-based compensation		1,517				1,517
Cash dividends declared			(12,623)			(12,623)
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			35,122			35,122
Other comprehensive income (loss)				2,150		2,150
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)	164,720
Common stock issued under stock compensation plans	$ 17	959				976
Common stock issued under dividend reinvestment and stock purchase plan (in shares)	823,902
Common stock issued under dividend reinvestment and stock purchase plan	$ 82	22,516				22,598
Stock-based compensation		2,434				2,434
Cash dividends declared			(14,133)			(14,133)
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			41,573			41,573
Other comprehensive income (loss)				(9,709)		(9,709)
Reclassification of stranded tax effects upon the adoption of ASU 2018-02			277	(277)	[1]
Repurchase of common stock	$ (8)	(1,533)				(1,541)
Repurchase of common stock (in shares)	(77,300)
Shares tendered upon the exercise of stock options	$ (1)	(365)				(366)
Shares tendered upon the exercise of stock options (in shares)	(14,549)
Shares withheld upon the vesting and conversion of RSUs (in shares)	(27,591)
Shares withheld upon the vesting and conversion of RSUs	$ (3)	(771)				(774)
Common stock issued under stock compensation plans (in shares)	174,164
Common stock issued under stock compensation plans	$ 17	727				744
Common stock issued under dividend reinvestment and stock purchase plan (in shares)	699,626
Common stock issued under dividend reinvestment and stock purchase plan	$ 70	18,169				18,239
Stock-based compensation		1,814				1,814
Cash dividends declared			(16,243)			(16,243)
Balance (in shares) at Dec. 31, 2018	25,422,740
Balance at Dec. 31, 2018	$ 2,542	$ 145,163	$ 249,922	$ (9,440)		$ 388,187

[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 "Adoption of New Accounting Standards" for more information regarding the effects of adopting ASU 2018-02.