UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance, beginning of period at Dec. 31, 2023	$ 382,340	$ 5,883	$ 1,566	$ 28,672	$ 355,873	$ (9,654)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	531	130		401
Purchase of treasury shares	(4,274)	(128)			(4,146)
Net income	4,570				4,570
Cash dividends on Class A and Class B common stock	(1,630)				(1,630)
Reclassification adjustment to net income, net of tax	76					76
Balance, end of period at Mar. 31, 2024	381,613	5,885	1,566	29,073	354,667	(9,578)
Balance, beginning of period at Dec. 31, 2023	382,340	5,883	1,566	28,672	355,873	(9,654)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	26,177
Balance, end of period at Sep. 30, 2024	397,310	5,732	1,566	31,621	367,814	(9,423)
Balance, beginning of period at Mar. 31, 2024	381,613	5,885	1,566	29,073	354,667	(9,578)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,389	11		1,378
Purchase of treasury shares	(3,285)	(108)			(3,177)
Net income	5,972				5,972
Cash dividends on Class A and Class B common stock	(1,676)				(1,676)
Reclassification adjustment to net income, net of tax	77					77
Balance, end of period at Jun. 30, 2024	384,090	5,788	1,566	30,451	355,786	(9,501)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,182	12		1,170
Purchase of treasury shares	(2,017)	(68)			(1,949)
Net income	15,635				15,635
Cash dividends on Class A and Class B common stock	(1,658)				(1,658)
Reclassification adjustment to net income, net of tax	78					78
Balance, end of period at Sep. 30, 2024	397,310	5,732	1,566	31,621	367,814	(9,423)
Balance, beginning of period at Dec. 31, 2024	404,947	5,730	1,566	34,340	373,363	(10,052)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,547	169		1,378
Purchase of treasury shares	(695)	(22)			(673)
Net income	4,900				4,900
Cash dividends on Class A and Class B common stock	(1,691)				(1,691)
Reclassification adjustment to net income, net of tax	109					109
Balance, end of period at Mar. 31, 2025	409,117	5,877	1,566	35,718	375,899	(9,943)
Balance, beginning of period at Dec. 31, 2024	404,947	5,730	1,566	34,340	373,363	(10,052)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,414
Balance, end of period at Sep. 30, 2025	426,402	5,896	1,564	40,016	388,652	(9,726)
Balance, beginning of period at Mar. 31, 2025	409,117	5,877	1,566	35,718	375,899	(9,943)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	2,514	9		2,505
Conversion of Class B to Class A shares	0	2	(2)
Net income	3,260				3,260
Cash dividends on Class A and Class B common stock	(1,879)				(1,879)
Reclassification adjustment to net income, net of tax	108					108
Balance, end of period at Jun. 30, 2025	413,120	5,888	1,564	38,223	377,280	(9,835)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,801	8		1,793
Net income	13,254				13,254
Cash dividends on Class A and Class B common stock	(1,882)				(1,882)
Reclassification adjustment to net income, net of tax	109					109
Balance, end of period at Sep. 30, 2025	$ 426,402	$ 5,896	$ 1,564	$ 40,016	$ 388,652	$ (9,726)