Condensed Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Shares [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock, Common
Shares Outstanding, Beginning Balance at Dec. 31, 2023		27,761,299
Stockholders' Equity, Beginning Balance at Dec. 31, 2023	$ 2,516,939	$ 301	$ 349,907	$ 2,301,348	$ (134,617)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	430,256			430,256
Stock options exercised, shares		310,696
Stock options exercised	13,034		(7,172)		20,206
Stock-based compensation expense	10,859		10,859
Repurchase of common shares, shares		(922,000)
Repurchase of common shares	(125,819)				(125,819)
Deferral of executive and director compensation	87		87
Deferred Compensation Arrangement with Individual, Shares Issued		55,059
Deferred Compensation Arrangement with Individual, Distribution Paid	0		(3,137)		3,137
Shares Outstanding, Ending Balance at Sep. 30, 2024		27,205,054
Stockholders' Equity, Ending Balance at Sep. 30, 2024	2,845,356	$ 301	350,544	2,731,604	(237,093)
Shares Outstanding, Beginning Balance at Jun. 30, 2024		27,403,908
Stockholders' Equity, Beginning Balance at Jun. 30, 2024	2,741,117	$ 301	350,554	2,586,155	(195,893)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	145,449			145,449
Stock options exercised, shares		123,146
Stock options exercised	5,485		(3,549)		9,034
Stock-based compensation expense	3,510		3,510
Repurchase of common shares, shares		(322,000)
Repurchase of common shares	(50,234)				(50,234)
Deferral of executive and director compensation	29		29
Deferred Compensation Arrangement with Individual, Shares Issued		0
Deferred Compensation Arrangement with Individual, Distribution Paid			0		0
Shares Outstanding, Ending Balance at Sep. 30, 2024		27,205,054
Stockholders' Equity, Ending Balance at Sep. 30, 2024	2,845,356	$ 301	350,544	2,731,604	(237,093)
Shares Outstanding, Beginning Balance at Dec. 31, 2024		27,063,023
Stockholders' Equity, Beginning Balance at Dec. 31, 2024	2,939,677	$ 301	348,705	2,865,073	(274,402)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	338,970			338,970
Stock options exercised, shares		160,200
Stock options exercised	8,312		(6,940)		15,252
Stock-based compensation expense	12,641		12,641
Repurchase of common shares, shares		(1,237,000)
Repurchase of common shares	(150,378)				(150,378)
Deferral of executive and director compensation	227		227
Deferred Compensation Arrangement with Individual, Shares Issued		162,286
Deferred Compensation Arrangement with Individual, Distribution Paid	0		(14,821)		14,821
Shares Outstanding, Ending Balance at Sep. 30, 2025		26,148,509
Stockholders' Equity, Ending Balance at Sep. 30, 2025	3,149,449	$ 301	339,812	3,204,043	(394,707)
Shares Outstanding, Beginning Balance at Jun. 30, 2025		26,339,786
Stockholders' Equity, Beginning Balance at Jun. 30, 2025	3,082,136	$ 301	344,536	3,097,553	(360,254)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	106,490			106,490
Stock options exercised, shares		120,200
Stock options exercised	6,448		(5,149)		11,597
Stock-based compensation expense	$ 4,525		4,525
Repurchase of common shares, shares	400,000	(355,000)
Repurchase of common shares	$ (50,179)				(50,179)
Deferral of executive and director compensation	29		29
Deferred Compensation Arrangement with Individual, Shares Issued		43,523
Deferred Compensation Arrangement with Individual, Distribution Paid	0		(4,129)		4,129
Shares Outstanding, Ending Balance at Sep. 30, 2025		26,148,509
Stockholders' Equity, Ending Balance at Sep. 30, 2025	$ 3,149,449	$ 301	$ 339,812	$ 3,204,043	$ (394,707)