Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2014	$ 4,607	$ 37,504	$ 71,452	$ (3,100)	$ (6,942)	$ 103,521
Net income			10,204			10,204
Other comprehensive income				(622)		(622)
Cash dividends declared			(3,139)			(3,139)
Treasury shares issued under employee stock option/purchase plans		6			86	92
Common stock issued under dividend reinvestment plan	52	1,194				1,246
Stock option compensation expense		74				74
Balance at Dec. 31, 2015	4,659	38,778	78,517	(3,722)	(6,856)	111,376
Net income			8,087			8,087
Other comprehensive income				(493)		(493)
Cash dividends declared			(3,523)			(3,523)
Acquisition of 34,048 shares of treasury stock					(795)	(795)
Treasury shares issued under employee stock option/purchase plans		4			16	20
Treasury shares issued under dividend reinvestment plan		296			822	1,118
Common stock issued under dividend reinvestment plan	25	528				553
Common stock issued under incentive stock option plan	4	58				62
Stock option compensation expense		88				88
Balance at Dec. 31, 2016	4,688	39,752	83,081	(4,215)	(6,813)	116,493
Net income			2,176			2,176
Other comprehensive income				(821)		(821)
Cash dividends declared			(4,031)			(4,031)
Treasury shares issued under employee stock option/purchase plans		32			125	157
Treasury shares issued under dividend reinvestment plan		434			557	991
Common stock issued under incentive stock option plan	1	17				18
Revaluation of net deferred tax assets			992	(992)
Stock option compensation expense		161				161
Balance at Dec. 31, 2017	$ 4,689	$ 40,396	$ 82,218	$ (6,028)	$ (6,131)	$ 115,144