Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock Outstanding [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock Outstanding [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]	Total
Balance (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018	$ 0	$ 0	$ (27)	$ 0	$ (27)
Balance at Dec. 31, 2018						$ 21,248	$ 73,960	$ 208,164	$ (7,705)	$ 295,667
Cash dividends declared						0	0	(11,725)	0	(11,725)
Issuance of shares of common stock pursuant to dividend reinvestment plan						358	8,776	0	0	9,134
Issuance of shares of common stock pursuant to exercise of stock options						25	412	0	0	437
Share based compensation expense						0	265	0	0	265
Net change in fair value of available-for-sale securities during the period, net of taxes						0	0	0	7,697	7,697
Net earnings for the quarter						0	0	28,072	0	28,072
Net earnings						0	0	28,072	0	28,072
Repurchase of common shares						(64)	(1,565)	0	0	(1,629)
Balance at Sep. 30, 2019						21,567	81,848	224,484	(8)	327,891
Balance at Jun. 30, 2019						21,390	77,331	220,100	(633)	318,188
Cash dividends declared						0	0	(5,882)	0	(5,882)
Issuance of shares of common stock pursuant to dividend reinvestment plan						175	4,408	0	0	4,583
Issuance of shares of common stock pursuant to exercise of stock options						2	26	0	0	28
Share based compensation expense						0	83	0	0	83
Net change in fair value of available-for-sale securities during the period, net of taxes						0	0	0	625	625
Net earnings for the quarter						0	0	10,266	0	10,266
Net earnings						0	0	10,266	0	10,266
Balance at Sep. 30, 2019						21,567	81,848	224,484	(8)	327,891
Balance at Dec. 31, 2019						21,586	82,249	232,456	693	336,984
Cash dividends declared						0	0	(13,013)	0	(13,013)
Issuance of shares of common stock pursuant to dividend reinvestment plan						361	9,695	0	0	10,056
Issuance of shares of common stock pursuant to exercise of stock options						21	326	0	0	347
Share based compensation expense						0	312	0	0	312
Net change in fair value of available-for-sale securities during the period, net of taxes						0	0	0	6,615	6,615
Net earnings for the quarter						0	0	29,590	0	29,590
Net earnings						0	0	29,590	0	29,590
Balance at Sep. 30, 2020						21,968	92,582	249,033	7,308	370,891
Balance at Jun. 30, 2020						21,789	87,592	244,038	7,292	360,711
Cash dividends declared						0	0	(6,537)	0	(6,537)
Issuance of shares of common stock pursuant to dividend reinvestment plan						178	4,870	0	0	5,048
Issuance of shares of common stock pursuant to exercise of stock options						1	21	0	0	22
Share based compensation expense						0	99	0	0	99
Net change in fair value of available-for-sale securities during the period, net of taxes						0	0	0	16	16
Net earnings for the quarter						0	0	11,532	0	11,532
Net earnings						0	0	11,532	0	11,532
Balance at Sep. 30, 2020						$ 21,968	$ 92,582	$ 249,033	$ 7,308	$ 370,891