Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Class A [Member] Retained Earnings [Member]	Common Class A [Member] AOCI Attributable to Parent [Member]	Common Class A [Member] Common Stock, Common Class A [Member]	Common Class A [Member] Common Stock, Common Class B [Member]	Common Class A [Member] Treasury Stock, Common [Member]	Common Class A [Member] Additional Paid-in Capital [Member]	Common Class A [Member]	Common Class B [Member] Retained Earnings [Member]	Common Class B [Member] AOCI Attributable to Parent [Member]	Common Class B [Member] Common Stock, Common Class A [Member]	Common Class B [Member] Common Stock, Common Class B [Member]	Common Class B [Member] Treasury Stock, Common [Member]	Common Class B [Member] Additional Paid-in Capital [Member]	Common Class B [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Common Stock, Common Class A [Member]	Common Stock, Common Class B [Member]	Treasury Stock, Common [Member]	Additional Paid-in Capital [Member]	Total
Balance at Dec. 31, 2021															$ 187,935	$ (18,863)	$ 214	$ 1,038	$ 0	$ 38,419	$ 208,743
Net earnings															5,064	0	0	0	0	0	5,064
Cash dividends declared on common stock	$ (129)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (129)	$ (727)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (727)
Forfeiture of restricted common stock															0	0	0	(1)	0	1	0
Foreign currency translation adjustment, net of taxes															0	(1,216)	0	0	0	0	(1,216)
Unrealized gains on interest rate swap cash flow hedge															0	2,984	0	0	0	0	2,984
Stock-based compensation expense															0	0	0	0	0	576	576
Change in unfunded SERP liability, net of taxes															0	61	0	0	0	0	61
Forfeiture of restricted common stock															(0)	(0)	(0)	1	(0)	(1)	(0)
Balance at Mar. 31, 2022															192,143	(17,034)	214	1,037	0	38,996	215,356
Balance at Dec. 31, 2021															187,935	(18,863)	214	1,038	0	38,419	208,743
Net earnings							6,327							32,322							38,649
Cash dividends declared on common stock							(386)							(2,176)
Foreign currency translation adjustment, net of taxes																					(16,352)
Unrealized holding gains on marketable securities, net of taxes																					(11)
Change in unfunded SERP liability, net of taxes																					182
Balance at Sep. 30, 2022															224,022	(28,983)	214	1,034	(349)	40,095	236,033
Balance at Mar. 31, 2022															192,143	(17,034)	214	1,037	0	38,996	215,356
Net earnings															17,038	0	0	0	0	0	17,038
Cash dividends declared on common stock	(129)	0	0	0	0	0	(129)	(726)	0	0	0	0	0	(726)
Forfeiture of restricted common stock															0	0	0	(1)	0	1	0
Foreign currency translation adjustment, net of taxes															0	(6,764)	0	0	0	0	(6,764)
Unrealized gains on interest rate swap cash flow hedge															0	1,008	0	0	0	0	1,008
Unrealized holding gains on marketable securities, net of taxes															0	(12)	0	0	0	0	(12)
Stock-based compensation expense															0	0	0	0	0	512	512
Change in unfunded SERP liability, net of taxes															0	61	0	0	0	0	61
Forfeiture of restricted common stock															(0)	(0)	(0)	1	(0)	(1)	(0)
Repurchase of treasury stock															0	0	0	0	(349)		(349)
Balance at Jun. 30, 2022															208,326	(22,741)	214	1,036	(349)	39,509	225,995
Net earnings							2,715							13,833	16,548	0	0	0	0	0	16,548
Cash dividends declared on common stock	(128)	0	0	0	0	0	(128)	(724)	0	0	0	0	0	(724)
Forfeiture of restricted common stock															0	0	0	(2)	0	2	0
Foreign currency translation adjustment, net of taxes															0	(8,372)	0	0	0	0	(8,372)
Unrealized gains on interest rate swap cash flow hedge															0	2,070	0	0	0	0	2,070
Unrealized holding gains on marketable securities, net of taxes															0	(1)	0	0	0	0	(1)
Stock-based compensation expense															0	0	0	0	0	584	584
Change in unfunded SERP liability, net of taxes															0	61	0	0	0	0	61
Forfeiture of restricted common stock															(0)	(0)	(0)	2	(0)	(2)	(0)
Balance at Sep. 30, 2022															224,022	(28,983)	214	1,034	(349)	40,095	236,033
Balance at Dec. 31, 2022															237,188	(16,546)	214	1,067	(349)	40,772	262,346
Net earnings															14,572	0	0	0	0	0	14,572
Cash dividends declared on common stock	(128)	0	0	0	0	0	(128)	(747)	0	0	0	0	0	(747)
Forfeiture of restricted common stock															0	0	0	(1)	0		0
Forfeiture of restricted common stock, APIC																				1
Foreign currency translation adjustment, net of taxes															0	1,998	0	0	0	0	1,998
Unrealized gains on interest rate swap cash flow hedge															0	(894)	0	0	0	0	(894)
Unrealized holding gains on marketable securities, net of taxes															0	1	0	0	0	0	1
Stock-based compensation expense															0	0	0	0	0	902	902
Change in unfunded SERP liability, net of taxes															0	13	0	0	0	0	13
Forfeiture of restricted common stock															(0)	(0)	(0)	1	(0)		(0)
Balance at Mar. 31, 2023															250,885	(15,428)	214	1,066	(349)	41,675	278,063
Balance at Dec. 31, 2022															237,188	(16,546)	214	1,067	(349)	40,772	262,346
Net earnings							9,907							51,888							61,795
Cash dividends declared on common stock							(385)							(2,235)
Foreign currency translation adjustment, net of taxes																					(2,857)
Unrealized holding gains on marketable securities, net of taxes																					1
Change in unfunded SERP liability, net of taxes																					41
Balance at Sep. 30, 2023															296,365	(19,370)	214	1,063	(349)	43,488	321,411
Balance at Mar. 31, 2023															250,885	(15,428)	214	1,066	(349)	41,675	278,063
Net earnings															27,775	0	0	0	0	0	27,775
Cash dividends declared on common stock	(128)	0	0	0	0	0	(128)	(742)	0	0	0	0	0	(742)
Forfeiture of restricted common stock															0	0	0	(3)	0		0
Forfeiture of restricted common stock, APIC																				3
Foreign currency translation adjustment, net of taxes															0	(2,231)	0	0	0	0	(2,231)
Unrealized gains on interest rate swap cash flow hedge															0	789	0	0	0	0	789
Stock-based compensation expense															0	0	0	0	0	950	950
Change in unfunded SERP liability, net of taxes															0	14	0	0	0	0	14
Issuance of restricted common stock															0	0	0	1	0	(1)	0
Forfeiture of restricted common stock															(0)	(0)	(0)	3	(0)		(0)
Balance at Jun. 30, 2023															277,790	(16,856)	214	1,064	(349)	42,627	304,490
Net earnings							3,117							16,331	19,448	0	0	0	0	0	19,448
Cash dividends declared on common stock	$ (128)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (128)	$ (745)	$ 0	$ 0	$ 0	$ 0	$ 0	$ (745)
Forfeiture of restricted common stock															0	0	0	(1)	0		0
Forfeiture of restricted common stock, APIC																				1
Foreign currency translation adjustment, net of taxes															0	(2,624)	0	0	0	0	(2,624)
Unrealized gains on interest rate swap cash flow hedge															0	96	0	0	0	0	96
Unrealized holding gains on marketable securities, net of taxes																					0
Stock-based compensation expense															0	0	0	0	0	860	860
Change in unfunded SERP liability, net of taxes															0	14	0	0	0	0	14
Forfeiture of restricted common stock															(0)	(0)	(0)	1	(0)		(0)
Balance at Sep. 30, 2023															$ 296,365	$ (19,370)	$ 214	$ 1,063	$ (349)	$ 43,488	$ 321,411