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, 2018	$ 303,503	$ 37,198		$ 38,082	$ 257,313	$ 580	$ (306)	$ (29,364)
Net earnings	34,903				34,903
Pension and postretirement benefits (net of tax effect)	333					333
Foreign currency translation	(509)					(509)
Cash dividends	(13,665)				(13,665)
Stock options exercised	963	2		832				129
Stock-based compensation	882			882
Purchase of common stock for treasury stock	(3,358)							(3,358)
Issuance of treasury stock	587			510				77
Balance at end of period at Sep. 30, 2019	323,639	37,200		40,306	278,551	404	(306)	(32,516)
Balance at beginning of period at Jun. 30, 2019	316,452	37,200		39,746	270,772	1,066	(306)	(32,026)
Net earnings	12,721				12,721
Pension and postretirement benefits (net of tax effect)	(16)					(16)
Foreign currency translation	(646)					(646)
Cash dividends	(4,942)				(4,942)
Stock options exercised	215			192				23
Stock-based compensation	328			328
Purchase of common stock for treasury stock	(521)							(521)
Issuance of treasury stock	48			40				8
Balance at end of period at Sep. 30, 2019	323,639	37,200		40,306	278,551	404	(306)	(32,516)
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)

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