Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	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 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 period	29,590	0	0	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 period	0	0	11,532	0	11,532
Balance at Sep. 30, 2020	21,968	92,582	249,033	7,308	370,891
Balance at Dec. 31, 2020	21,987	93,034	257,935	7,165	380,121
Cash dividends declared	0	0	(14,910)	0	(14,910)
Issuance of shares of common stock pursuant to dividend reinvestment plan	373	10,815	0	0	11,188
Issuance of shares of common stock pursuant to exercise of stock options	29	544	0	0	573
Share based compensation expense	0	362	0	0	362
Net change in fair value of available-for-sale securities during the period, net of taxes	0	0	0	(8,530)	(8,530)
Net earnings for the period	0	0	35,625	0	35,625
Balance at Sep. 30, 2021	22,389	104,755	278,650	(1,365)	404,429
Balance at Jun. 30, 2021	22,170	98,321	273,622	1,492	395,605
Cash dividends declared	0	0	(8,314)	0	(8,314)
Issuance of shares of common stock pursuant to dividend reinvestment plan	206	6,080	0	0	6,286
Issuance of shares of common stock pursuant to exercise of stock options	13	239	0	0	252
Share based compensation expense	0	115	0	0	115
Net change in fair value of available-for-sale securities during the period, net of taxes	0	0	0	(2,857)	(2,857)
Net earnings for the period	0	0	13,342	0	13,342
Balance at Sep. 30, 2021	$ 22,389	$ 104,755	$ 278,650	$ (1,365)	$ 404,429