Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Total
Balance (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018			$ (199)				$ (199)
Balance at Dec. 31, 2018	$ 23,629	$ 134,506		$ 22,837	$ (2,226)	$ 0		$ 178,746
Net income				4,091				4,091
Other comprehensive income (loss), net of tax					1,399			1,399
Cash dividends				(1,512)				(1,512)
Stock-based compensation		135						135
Forfeiture and withheld shares of restricted stock		2				(4)		(2)
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan	17	132						149
Balance at Mar. 31, 2019	23,646	134,775		25,217	(827)	(4)		182,807
Balance (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018			$ (199)				$ (199)
Balance at Dec. 31, 2018	23,629	134,506		22,837	(2,226)	0		178,746
Net income								14,153
Other comprehensive income (loss), net of tax								3,735
Balance at Sep. 30, 2019	24,819	144,114		21,971	1,509	(3,040)		189,373
Balance at Mar. 31, 2019	23,646	134,775		25,217	(827)	(4)		182,807
Net income				4,859				4,859
Other comprehensive income (loss), net of tax					1,719			1,719
Cash dividends				(1,513)				(1,513)
Stock-based compensation		118						118
Repurchased stock						(762)		(762)
Forfeiture and withheld shares of restricted stock		5				(5)		0
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan	9	128				9		146
Issuance of shares under the stock option plan		(69)				88		19
Issuance of shares under employee stock purchase plan		(14)				141		127
Balance at Jun. 30, 2019	23,655	134,943		28,563	892	(533)		187,520
Net income				5,203				5,203
Other comprehensive income (loss), net of tax					617			617
Cash dividends				(1,508)				(1,508)
5% common stock dividend, at fair value	1,164	9,123		(10,287)				0
Stock-based compensation		142						142
Repurchased stock						(2,768)		(2,768)
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan		6				136		142
Issuance of shares under the stock option plan		(86)				111		25
Issuance of shares of stock-based compensation awards		(14)				14		0
Balance at Sep. 30, 2019	24,819	144,114		21,971	1,509	(3,040)		189,373
Balance at Dec. 31, 2019	24,390	140,450		25,019	1,309	0		191,168
Net income				(2,989)				(2,989)
Other comprehensive income (loss), net of tax					2,798			2,798
Cash dividends				(1,561)				(1,561)
Stock-based compensation		120						120
Repurchased stock						(87)		(87)
Forfeiture and withheld shares of restricted stock						(2)		(2)
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan	17	132						149
Issuance of shares of stock-based compensation awards	16	(16)						0
Balance at Mar. 31, 2020	24,423	140,686		20,469	4,107	(89)		189,596
Balance at Dec. 31, 2019	24,390	140,450		25,019	1,309	0		191,168
Net income								3,685
Other comprehensive income (loss), net of tax								2,680
Balance at Sep. 30, 2020	24,489	141,184		24,601	3,989	(2)		194,261
Balance at Mar. 31, 2020	24,423	140,686		20,469	4,107	(89)		189,596
Net income				3,050				3,050
Other comprehensive income (loss), net of tax					334			334
Cash dividends				(1,562)				(1,562)
Stock-based compensation		130						130
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan	18	44				89		151
Issuance of shares under the stock option plan	2	3						5
Issuance of shares of stock-based compensation awards	(2)	2						0
Issuance of shares under employee stock purchase plan	28	103						131
Balance at Jun. 30, 2020	24,469	140,968		21,957	4,441	0		191,835
Net income				3,624				3,624
Other comprehensive income (loss), net of tax					(452)			(452)
Cash dividends				(980)				(980)
Stock-based compensation		139						139
Forfeiture and withheld shares of restricted stock						(2)		(2)
Issuance and reissuance of stock:
Issuance of shares under the dividend reinvestment and stock purchase plan	18	79						97
Issuance of shares of stock-based compensation awards	2	(2)						0
Balance at Sep. 30, 2020	$ 24,489	$ 141,184		$ 24,601	$ 3,989	$ (2)		$ 194,261