CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Impact of adoption of ASC 326	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Impact of adoption of ASC 326	Treasury Stock	Accumulated Other Comprehensive Income
Beginning balance at Dec. 31, 2019	$ 261,551	$ (3,593)	$ 12,905	$ 186,692	$ 98,239	$ (3,593)	$ (34,492)	$ (1,793)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	17,487				17,487
Other comprehensive income (loss)	11,364							11,364
10% stock dividend
Exercise of stock options	72		4	68
Purchase of treasury stock	(14,110)						(14,110)
Stock based compensation	494			494
Dividends: Common Stock	(6,412)				(6,412)
Ending balance at Sep. 30, 2020	266,853		12,909	187,254	105,721		(48,602)	9,571
Beginning balance at Jun. 30, 2020	258,875		12,908	187,073	97,788		(47,969)	9,075
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	10,134				10,134
Other comprehensive income (loss)	496							496
Exercise of stock options	0		1	(1)
Purchase of treasury stock	(633)						(633)
Stock based compensation	182			182
Dividends: Common Stock	(2,201)				(2,201)
Ending balance at Sep. 30, 2020	266,853		12,909	187,254	105,721		(48,602)	9,571
Beginning balance at Dec. 31, 2020	272,643		12,952	188,032	113,449		(51,419)	9,629
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	30,647				30,647
Other comprehensive income (loss)	(268)							(268)
10% stock dividend	35,947		1,094	34,853	(35,947)
Exercise of stock options	1,113		48	1,065
Restricted stock grants			4	(4)
Stock based compensation	512			512
Dividends: Common Stock	(7,239)				(7,239)
Ending balance at Sep. 30, 2021	297,408		14,098	224,458	100,910		(51,419)	9,361
Beginning balance at Jun. 30, 2021	287,729		14,074	223,822	94,073		(51,419)	7,179
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	9,253				9,253
Other comprehensive income (loss)	2,182							2,182
Exercise of stock options	477		20	457
Restricted stock grants	0		4	(4)
Stock based compensation	183			183
Dividends: Common Stock	(2,416)				2,416
Ending balance at Sep. 30, 2021	$ 297,408		$ 14,098	$ 224,458	$ 100,910		$ (51,419)	$ 9,361