Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock at $1 par value	[1]	Capital in excess of par value	Reinvested earnings	Employee benefit stock	Accumulated other comprehensive income (loss)	Treasury stock
Balance at beginning of period at Dec. 31, 2016	$ 256,209	$ 37,122		$ 28,022	$ 223,876	$ (614)	$ (11,635)	$ (20,562)
Net earnings	34,571				34,571
Pension and postretirement benefits (net of tax effect)	(1,102)						(1,102)
Foreign currency translation	1,844						1,844
Cash dividends	(14,223)				(14,223)
Stock options exercised	1,871	43		1,798				30
ESSOP transactions	359			205		154
Stock-based compensation	1,725			1,725
Purchase of common stock for treasury stock	(4,402)							(4,402)
Issuance of treasury stock	600			432				168
Balance at end of period at Dec. 31, 2017	277,452	37,165		32,182	244,224	(460)	(10,893)	(24,766)
Net earnings	27,790				27,790
Pension and postretirement benefits (net of tax effect)	13,657						13,657
Foreign currency translation	(484)						(484)
Cash dividends	(16,273)				(16,273)
ASU adoption impact | Accounting Standards Update 2014-09	(128)				(128)
ASU adoption impact | Accounting Standards Update 2018-02	1,700				1,700		(1,700)
Stock options exercised	1,511	33		1,410				68
ESSOP transactions	76			(78)		154
Stock-based compensation	4,174			4,174
Purchase of common stock for treasury stock	(4,795)							(4,795)
Issuance of treasury stock	523			394				129
Balance at end of period at Dec. 31, 2018	303,503	37,198		38,082	257,313	(306)	580	(29,364)
Net earnings	47,177				47,177
Pension and postretirement benefits (net of tax effect)	(97)						(97)
Foreign currency translation	(58)						(58)
Cash dividends	(18,611)				(18,611)
Stock options exercised	1,961	2		1,708				251
ESSOP transactions	553			401		152
Stock-based compensation	1,214			1,214
Purchase of common stock for treasury stock	(5,207)							(5,207)
Issuance of treasury stock	633			551				82
Balance at end of period at Dec. 31, 2019	$ 331,068	$ 37,200		$ 41,956	$ 285,879	$ (154)	$ 425	$ (34,238)

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