Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2016	$ 0	$ 21,067	$ 106,102	$ 28,909	$ (1,121)	$ 0	$ 154,957
Net income				10,514			10,514
Other comprehensive income (loss), net of tax					848		848
Cash dividends				(3,418)			(3,418)
5% stock dividend		1,058	12,607	(13,665)			0
Stock-based compensation			509				509
Forfeiture of restricted stock			4			(9)	(5)
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan		32	317				349
Issuance of shares under the stock option plan		28	157				185
Issuance of shares of stock-based compensation awards		18	(18)				0
Issuance of shares under employee stock purchase plan		8	103			4	115
Balance at Sep. 30, 2017	0	22,211	119,781	22,340	(273)	(5)	164,054
Balance at Dec. 31, 2017	0	22,265	120,052	22,860	(958)	0	164,219
Net income				15,197			15,197
Other comprehensive income (loss), net of tax					(2,967)		(2,967)
Cash dividends				(4,151)			(4,151)
5% stock dividend		1,119	12,907	(14,026)			0
Stock-based compensation			457				457
Forfeiture of restricted stock and withheld shares			5			(75)	(70)
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan		31	322			57	410
Issuance of shares under the stock option plan		70	305			9	384
Issuance of shares of stock-based compensation awards		10	(10)				0
Issuance of shares under employee stock purchase plan		9	105			4	118
Balance at Sep. 30, 2018	$ 0	$ 23,504	$ 134,143	$ 19,880	$ (3,925)	$ (5)	$ 173,597