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	22,182				22,182
Pension and postretirement benefits (net of tax effect)	349					349
Foreign currency translation	137					137
Cash dividends	(8,723)				(8,723)
Stock options exercised	748	2		640				106
Stock-based compensation	554			554
Purchase of common stock for treasury stock	(2,837)							(2,837)
Issuance of treasury stock	539			470				69
Balance at end of period at Jun. 30, 2019	316,452	37,200		39,746	270,772	1,066	(306)	(32,026)
Balance at beginning of period at Mar. 31, 2019	308,613	37,200		38,756	263,777	311	(306)	(31,125)
Net earnings	11,358				11,358
Pension and postretirement benefits (net of tax effect)	360					360
Foreign currency translation	395					395
Cash dividends	(4,363)				(4,363)
Stock options exercised	277			243				34
Stock-based compensation	289			289
Purchase of common stock for treasury stock	(964)							(964)
Issuance of treasury stock	487			458				29
Balance at end of period at Jun. 30, 2019	316,452	37,200		39,746	270,772	1,066	(306)	(32,026)
Balance at beginning of period at Dec. 31, 2019	331,068	37,200		41,956	285,879	425	(154)	(34,238)
Net earnings	21,388				21,388
Pension and postretirement benefits (net of tax effect)	2					2
Foreign currency translation	(182)					(182)
Cash dividends	(9,897)				(9,897)
Stock options exercised	478	20		438				20
Stock-based compensation	705			705
Purchase of common stock for treasury stock	(2,873)							(2,873)
Issuance of treasury stock	454			357				97
Balance at end of period at Jun. 30, 2020	341,143	37,220		43,456	297,370	245	(154)	(36,994)
Balance at beginning of period at Mar. 31, 2020	335,721	37,220		42,690	292,785	(201)	(154)	(36,619)
Net earnings	9,534				9,534
Pension and postretirement benefits (net of tax effect)	1					1
Foreign currency translation	445					445
Cash dividends	(4,949)				(4,949)
Stock-based compensation	398			398
Purchase of common stock for treasury stock	(406)							(406)
Issuance of treasury stock	399			368				31
Balance at end of period at Jun. 30, 2020	$ 341,143	$ 37,220		$ 43,456	$ 297,370	$ 245	$ (154)	$ (36,994)

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