Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ 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, 2022															$ 237,188	$ (16,546)	$ 214	$ 1,067	$ (349)	$ 40,772	$ 262,346
Balance (in shares) at Dec. 31, 2022																	2,142	10,643
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 (in shares)																	0	(10)
Forfeiture of restricted common stock															0	0	$ 0	$ (1)	0		0
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, net of taxes of $0															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
Net earnings															14,572	0	0	0	0	0	14,572
Forfeiture of restricted common stock															(0)	(0)	$ (0)	$ 1	(0)		(0)
Forfeiture of restricted common stock (in shares)																	0	(10)
Forfeiture of restricted common stock																				(1)
Forfeiture of restricted common stock																				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
Foreign currency translation adjustment, net of taxes															0	1,998	0	0	0	0	1,998
Balance at Mar. 31, 2023															250,885	(15,428)	$ 214	$ 1,066	(349)	41,675	278,063
Balance (in shares) at Mar. 31, 2023																	2,142	10,633
Balance at Dec. 31, 2022															237,188	(16,546)	$ 214	$ 1,067	(349)	40,772	262,346
Balance (in shares) at Dec. 31, 2022																	2,142	10,643
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
Net earnings							9,907							51,888							61,795
Change in unfunded SERP liability, net of taxes																					41
Foreign currency translation adjustment, net of taxes																					(2,857)
Balance at Sep. 30, 2023															296,365	(19,370)	$ 214	$ 1,063	(349)	43,488	321,411
Balance (in shares) at Sep. 30, 2023																	2,142	10,638
Balance at Mar. 31, 2023															250,885	(15,428)	$ 214	$ 1,066	(349)	41,675	278,063
Balance (in shares) at Mar. 31, 2023																	2,142	10,633
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)
Issuance of restricted common stock															0	0	$ 0	$ 1	0	(1)	0
Issuance of restricted common stock (in shares)																	0	10
Forfeiture of restricted common stock															0	0	$ 0	$ (3)	0		0
Forfeiture of restricted common stock (in shares)																	0	(5)
Forfeiture of restricted common stock															0	0	$ 0	$ (3)	0		0
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, net of taxes of $0															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
Net earnings															27,775	0	0	0	0	0	27,775
Forfeiture of restricted common stock															(0)	(0)	$ (0)	$ 3	(0)		(0)
Forfeiture of restricted common stock (in shares)																	0	(5)
Forfeiture of restricted common stock																				(3)
Forfeiture of restricted common stock																				3
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
Foreign currency translation adjustment, net of taxes															0	(2,231)	0	0	0	0	(2,231)
Balance at Jun. 30, 2023															277,790	(16,856)	$ 214	$ 1,064	(349)	42,627	304,490
Balance (in shares) at Jun. 30, 2023																	2,142	10,638
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															0	0	0	(1)	0		0
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, net of taxes of $0															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
Net earnings							3,117							16,331	19,448	0	0	0	0	0	19,448
Forfeiture of restricted common stock															(0)	(0)	(0)	1	(0)		(0)
Forfeiture of restricted common stock																				(1)
Forfeiture of restricted common stock																				1
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
Foreign currency translation adjustment, net of taxes															0	(2,624)	0	0	0	0	(2,624)
Balance at Sep. 30, 2023															296,365	(19,370)	$ 214	$ 1,063	(349)	43,488	321,411
Balance (in shares) at Sep. 30, 2023																	2,142	10,638
Balance at Dec. 31, 2023															307,510	(12,037)	$ 214	$ 1,065	(454)	44,260	340,558
Balance (in shares) at Dec. 31, 2023																	2,142	10,620
Net earnings															15,874	0	$ 0	$ 0	0	0	15,874
Cash dividends declared on common stock	(129)	0	0	0	0	0	(129)	(747)	0	0	0	0	0	(747)
Issuance of restricted common stock															0	0	$ 0	$ 6	$ 0	$ (6)	0
Issuance of restricted common stock (in shares)																	0	58
Forfeiture of restricted common stock															0	0	$ 0	$ (6)			0
Forfeiture of restricted common stock (in shares)																	0	0	0	0
Forfeiture of restricted common stock															0	0	$ 0	$ (6)			0
Purchases of common stock															0	0	$ (1)	$ (10)	$ (6,283)		(6,283)
Purchases of common stock (in shares)																	(11)	(98)
Purchases of common stock																				$ 11
Foreign currency translation adjustment, net of taxes															0	(3,776)	$ 0	$ 0	0	0	(3,776)
Unrealized gains on interest rate swap cash flow hedge, net of taxes of $0															0	340	0	0	0	0	340
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	804	804
Change in unfunded SERP liability, net of taxes															0	15	0	0	0	0	15
Net earnings															15,874	0	0	0	$ 0	$ 0	15,874
Forfeiture of restricted common stock															(0)	(0)	$ (0)	$ 6			(0)
Forfeiture of restricted common stock (in shares)																	0	0	0	0
Purchases of common stock (in shares)																	11	98
Purchases of common stock																				$ 11
Stock-based compensation expense															0	0	$ 0	$ 0	$ 0	804	804
Change in unfunded SERP liability, net of taxes															0	15	0	0	0	0	15
Foreign currency translation adjustment, net of taxes															0	(3,776)	0	0	0	0	(3,776)
Balance at Mar. 31, 2024															322,508	(15,457)	$ 213	$ 1,061	(6,737)	45,069	346,657
Balance (in shares) at Mar. 31, 2024																	2,131	10,574
Balance at Dec. 31, 2023															307,510	(12,037)	$ 214	$ 1,065	(454)	44,260	340,558
Balance (in shares) at Dec. 31, 2023																	2,142	10,620
Net earnings							6,872							35,888							42,760
Cash dividends declared on common stock							(381)							(2,190)
Foreign currency translation adjustment, net of taxes																					1,317
Unrealized holding gains on marketable securities, net of taxes																					1
Change in unfunded SERP liability, net of taxes																					46
Net earnings							6,872							35,888							42,760
Change in unfunded SERP liability, net of taxes																					46
Foreign currency translation adjustment, net of taxes																					1,317
Balance at Sep. 30, 2024															347,702	(12,155)	$ 212	$ 1,046	(16,507)	47,064	367,362
Balance (in shares) at Sep. 30, 2024																	2,115	10,432
Balance at Mar. 31, 2024															322,508	(15,457)	$ 213	$ 1,061	(6,737)	45,069	346,657
Balance (in shares) at Mar. 31, 2024																	2,131	10,574
Net earnings															18,806	0	$ 0	$ 0	0	0	18,806
Cash dividends declared on common stock	(127)	0	0	0	0	0	(127)	(725)	0	0	0	0	0	(725)
Forfeiture of restricted common stock															0	0	$ 0	$ (1)	0		(1)
Forfeiture of restricted common stock (in shares)																	0	(4)
Forfeiture of restricted common stock															0	0	$ 0	$ (1)	0		(1)
Purchases of common stock															0	0	$ (1)	$ (12)	(7,892)		(7,893)
Purchases of common stock (in shares)																	(10)	(117)
Purchases of common stock																				12
Foreign currency translation adjustment, net of taxes															0	(999)	$ 0	$ 0	0	0	(999)
Unrealized gains on interest rate swap cash flow hedge, net of taxes of $0															0	(291)	0	0	0	0	(291)
Stock-based compensation expense															0	0	0	0	0	971	971
Change in unfunded SERP liability, net of taxes															0	15	0	0	0	0	15
Net earnings															18,806	0	0	0	0	0	18,806
Forfeiture of restricted common stock															(0)	(0)	$ (0)	$ 1	(0)		1
Forfeiture of restricted common stock (in shares)																	0	(4)
Forfeiture of restricted common stock																				2
Purchases of common stock (in shares)																	10	117
Purchases of common stock																				12
Forfeiture of restricted common stock																				(2)
Stock-based compensation expense															0	0	$ 0	$ 0	0	971	971
Change in unfunded SERP liability, net of taxes															0	15	0	0	0	0	15
Foreign currency translation adjustment, net of taxes															0	(999)	0	0	0	0	(999)
Balance at Jun. 30, 2024															340,462	(16,732)	$ 212	$ 1,048	(14,629)	46,054	356,415
Balance (in shares) at Jun. 30, 2024																	2,121	10,453
Net earnings							1,297							6,783	8,080	0	$ 0	$ 0	0	0	8,080
Cash dividends declared on common stock	$ (125)	$ 0	$ 0	$ 0	$ 0	$ 0	(125)	$ (715)	$ 0	$ 0	$ 0	$ 0	$ 0	(715)
Purchases of common stock															0	0	$ 0	$ (2)	(1,878)		(1,877)
Purchases of common stock (in shares)																	6	21
Purchases of common stock																				3
Foreign currency translation adjustment, net of taxes															0	6,092	$ 0	$ 0	0	0	6,092
Unrealized gains on interest rate swap cash flow hedge, net of taxes of $0															0	(1,531)	0	0	0	0	(1,531)
Unrealized holding gains on marketable securities, net of taxes																					0
Stock-based compensation expense															0	0	0	0	0	1,007	1,007
Change in unfunded SERP liability, net of taxes															0	16	0	0	0	0	16
Net earnings							$ 1,297							$ 6,783	8,080	0	$ 0	$ 0	0	0	8,080
Purchases of common stock (in shares)																	(6)	(21)
Purchases of common stock																				3
Stock-based compensation expense															0	0	$ 0	$ 0	0	1,007	1,007
Change in unfunded SERP liability, net of taxes															0	16	0	0	0	0	16
Foreign currency translation adjustment, net of taxes															0	6,092	0	0	0	0	6,092
Balance at Sep. 30, 2024															$ 347,702	$ (12,155)	$ 212	$ 1,046	$ (16,507)	$ 47,064	$ 367,362
Balance (in shares) at Sep. 30, 2024																	2,115	10,432