Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Equity
Balance at beginning		$ 244,493			$ 244,493
Net earnings	$ 5,607		$ 4,864		12,257	$ 12,309
Foreign currency translation adjustments	61		262		(1,031)	(44)
Pension liability adjustments, net of tax	(73)		$ (84)		(146)	$ (183)
Balance at ending	$ 251,204				$ 251,204
Cash dividends declared (in dollars per share)	$ 0.26	$ 0.25	$ 0.25	$ 0.24	$ 0.51	$ 0.49
Common stock
Equity
Balance at beginning	$ 9,508	$ 9,497	$ 9,523	$ 9,584	$ 9,497	$ 9,584
Stock options exercised, net of shares withheld for employee taxes and strike price	1	11	29	1
Shares purchased and retired	(18)		(23)	(62)
Balance at ending	9,491	9,508	9,529	9,523	9,491	9,529
Capital in excess of par value
Equity
Balance at beginning	72,016	71,661	70,828	70,475	71,661	70,475
Stock options exercised, net of shares withheld for employee taxes and strike price	(1)	(12)	(194)	15
Share-based compensation expense	331	367	337	338
Balance at ending	72,346	72,016	70,971	70,828	72,346	70,971
Reinvested earnings
Equity
Balance at beginning	184,914	180,646	167,717	164,039	180,646	164,039
Net earnings	5,607	6,650	4,864	7,445
Cash dividends declared	(2,467)	(2,377)	(2,377)	(2,289)
Shares purchased and retired	(491)	(5)	(571)	(1,478)
Balance at ending	187,563	184,914	169,633	167,717	187,563	169,633
Accumulated other comprehensive loss
Equity
Balance at beginning	(18,330)	(17,311)	(20,400)	(20,193)	(17,311)	(20,193)
Foreign currency translation adjustments	61	(1,092)	262	(306)
Pension liability adjustments, net of tax	73	73	84	99
Balance at ending	$ (18,196)	$ (18,330)	$ (20,054)	$ (20,400)	$ (18,196)	$ (20,054)