Statements of Consolidated Shareholders' Equity $ in Thousands	USD ($) $ / shares shares	3.99% Senior unsecured notes [Member]	4.00% Senior unsecured notes [Member]	Common shares USD ($)	Additional paid-in capital USD ($)	Common shares subscribed, unissued USD ($)	Retained earnings USD ($)	Accumulated other comprehensive income (loss), net of tax USD ($)	Treasury Stock, Common USD ($)	Common shares subscription receivable USD ($)
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2020	$ 79,674			$ 37,801	$ 110,069	$ 0	$ 206,711	$ (4,547)	$ (270,360)	$ 0
Increase (decrease) in stockholders' equity [Roll Forward]
Net income	65,699						65,699
Change in 401KSOP and ESOP related shares	(16,550)			578	12,405		(29,533)
Shares sold to employees	21,190				10,899				10,291
Options exercised	4,330				(443)				4,773
Stock-based compensation	$ 2,967				2,967
Dividends declared per share | $ / shares	$ 0.06
Dividends	$ (2,898)						(2,898)
Defined benefit pension plans	290
Net of tax amount	374							374
Shares purchased	(50,946)								(50,946)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2021	103,840			38,379	135,897	0	239,979	(4,173)	(306,242)	0
Balance at the end of the year at Dec. 31, 2021	$ (4,173)
Common shares, at end of year at Dec. 31, 2021 | shares	76,435,752
Balance at the beginning of the year at Dec. 31, 2020	$ (4,547)
Increase (decrease) in stockholders' equity [Roll Forward]
Net income	61,290						61,290
Change in 401KSOP and ESOP related shares	(48)			171	3,517		(3,736)
Shares sold to employees	30,235				16,357				13,878
Options exercised	2,644				(673)				3,317
Options exercised	6,318				1,560	23,864			1,239	(20,345)
Stock-based compensation	$ 6,170				6,170
Dividends declared per share | $ / shares	$ 0.08
Dividends	$ (3,540)						(3,540)
Defined benefit pension plans	641
Net of tax amount	(1,415)							(1,415)
Shares purchased	(75,694)								(75,694)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2022	129,800			38,550	162,828	23,864	293,993	(5,588)	(363,502)	(20,345)
Balance at the end of the year at Dec. 31, 2022	$ (5,588)
Common shares, at end of year at Dec. 31, 2022 | shares	76,639,510
Common shares, at beginning of year at Dec. 31, 2021 | shares	76,435,752
Balance at the beginning of the year at Dec. 31, 2021	$ (4,173)
Increase (decrease) in stockholders' equity [Roll Forward]
Shares purchased, shares | shares	4,165,582
Shares sold | shares	(1,771,075)
Net income	$ 72,140						72,140
Change in 401KSOP and ESOP related shares	(18,692)			758	12,397		(31,847)
Shares sold to employees	38,664				18,252				20,412
Options exercised	2,232				(1,707)				3,939
Options exercised	3,953				692	(1,032)			611	3,682
Stock-based compensation	$ 5,500				5,500
Dividends declared per share | $ / shares	$ 0.09
Dividends	$ (3,850)						(3,850)
Defined benefit pension plans	(77)
Net of tax amount	803							803
Shares purchased	(78,076)								(78,076)
Stockholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2023	$ 152,474			$ 39,308	$ 197,962	$ 22,832	$ 330,436	$ (4,785)	$ (416,616)	$ (16,663)
Increase (decrease) in stockholders' equity [Roll Forward]
Stock split, conversion ratio	2
Balance at the end of the year at Dec. 31, 2023	$ (4,785)
Common shares, at end of year at Dec. 31, 2023 | shares	77,328,434
Common shares, at beginning of year at Dec. 31, 2022 | shares	76,639,510
Balance at the beginning of the year at Dec. 31, 2022	$ (5,588)
Increase (decrease) in stockholders' equity [Roll Forward]
Common shares, subscribed, value	$ (26,720)
Common shares, subscribed, shares | shares	(1,476,250)
Shares purchased, shares | shares	3,972,974
Shares sold | shares	(2,014,365)
Senior unsecured notes, interest rate		3.99%	4.00%