Consolidated Condensed Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock at $1 par value	[1]	Capital in excess of par value	Reinvested earnings	Accumulated other comprehensive income (loss)	Employee benefit stock	Treasury stock (at cost)
Balance at beginning of period at Dec. 31, 2019	$ 331,068	$ 37,200		$ 41,956	$ 285,879	$ 425	$ (154)	$ (34,238)
Net earnings	36,249				36,249
Pension and postretirement benefits (net of tax effect)	(9)					(9)
Foreign currency translation	268					268
Cash dividends	(15,132)				(15,132)
Stock options exercised	505	20		458				27
Stock-based compensation	1,041			1,041
Purchase of common stock for treasury stock	(2,934)							(2,934)
Issuance of treasury stock	487			395				92
Balance at end of period at Sep. 30, 2020	351,543	37,220		43,850	306,996	684	(154)	(37,053)
Balance at beginning of period at Jun. 30, 2020	341,143	37,220		43,456	297,370	245	(154)	(36,994)
Net earnings	14,861				14,861
Pension and postretirement benefits (net of tax effect)	(11)					(11)
Foreign currency translation	450					450
Cash dividends	(5,235)				(5,235)
Stock options exercised	27			20				7
Stock-based compensation	336			336
Purchase of common stock for treasury stock	(61)							(61)
Issuance of treasury stock	33			38				(5)
Balance at end of period at Sep. 30, 2020	351,543	37,220		43,850	306,996	684	$ (154)	(37,053)
Balance at beginning of period at Dec. 31, 2020	361,259	37,221		44,964	314,850	1,313		(37,089)
Net earnings	43,608				43,608
Pension and postretirement benefits (net of tax effect)	9					9
Foreign currency translation	(155)					(155)
Cash dividends	(16,408)				(16,408)
Stock options exercised	2,037			1,623				414
Stock-based compensation	1,537			1,537
Purchase of common stock for treasury stock	(460)							(460)
Issuance of treasury stock	397			308				89
Balance at end of period at Sep. 30, 2021	391,824	37,221		48,432	342,050	1,167		(37,046)
Balance at beginning of period at Jun. 30, 2021	381,847	37,221		46,500	332,104	3,411		(37,389)
Net earnings	15,855				15,855
Pension and postretirement benefits (net of tax effect)	4					4
Foreign currency translation	(2,248)					(2,248)
Cash dividends	(5,909)				(5,909)
Stock options exercised	1,685			1,342				343
Stock-based compensation	590			590
Balance at end of period at Sep. 30, 2021	$ 391,824	$ 37,221		$ 48,432	$ 342,050	$ 1,167		$ (37,046)

[1] Each common share of stock equals $1 par value; therefore, the number of common shares is the same as the dollar value.