Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Equity
Balance at beginning			$ 244,493				$ 244,493
Net earnings	$ 8,063			$ 9,337			20,320	$ 21,646
Foreign currency translation adjustments	913			(773)			(118)	(817)
Pension liability adjustments, net of tax	(79)			$ (92)			(225)	$ (275)
Balance at ending	$ 258,123						$ 258,123
Cash dividends declared (in dollars per share)	$ 0.26	$ 0.26	$ 0.25	$ 0.25	$ 0.25	$ 0.24	$ 0.77	$ 0.74
Common stock
Equity
Balance at beginning	$ 9,491	$ 9,508	$ 9,497	$ 9,529	$ 9,523	$ 9,584	$ 9,497	$ 9,584
Stock options exercised, net of shares withheld for employee taxes and strike price	15	1	11	6	29	1
Issuance of restricted stock	55			28
Restricted stock forfeited				(2)
Shares purchased and retired	(2)	(18)		(50)	(23)	(62)
Balance at ending	9,559	9,491	9,508	9,511	9,529	9,523	9,559	9,511
Capital in excess of par value
Equity
Balance at beginning	72,346	72,016	71,661	70,971	70,828	70,475	71,661	70,475
Stock options exercised, net of shares withheld for employee taxes and strike price	(18)	(1)	(12)	3	(194)	15
Issuance of restricted stock	(55)			(28)
Restricted stock forfeited				2
Share-based compensation expense	388	331	367	321	337	338
Balance at ending	72,661	72,346	72,016	71,269	70,971	70,828	72,661	71,269
Reinvested earnings
Equity
Balance at beginning	187,563	184,914	180,646	169,633	167,717	164,039	180,646	164,039
Net earnings	8,063	5,607	6,650	9,337	4,864	7,445
Cash dividends declared	(2,468)	(2,467)	(2,377)	(2,377)	(2,377)	(2,289)
Shares purchased and retired	(51)	(491)	(5)	(1,255)	(571)	(1,478)
Balance at ending	193,107	187,563	184,914	175,338	169,633	167,717	193,107	175,338
Accumulated other comprehensive loss
Equity
Balance at beginning	(18,196)	(18,330)	(17,311)	(20,054)	(20,400)	(20,193)	(17,311)	(20,193)
Foreign currency translation adjustments	913	61	(1,092)	(773)	262	(306)
Pension liability adjustments, net of tax	79	73	73	92	84	99
Balance at ending	$ (17,204)	$ (18,196)	$ (18,330)	$ (20,735)	$ (20,054)	$ (20,400)	$ (17,204)	$ (20,735)