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, 2022		27,440,083
Stockholders' Equity, Beginning Balance at Dec. 31, 2022	$ 2,070,725	$ 301	$ 352,639	$ 1,835,983	$ (118,198)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	221,067			221,067
Stock options exercised, shares		495,066
Stock options exercised	16,569		(5,299)		21,868
Stock-based compensation expense	4,324		4,324
Repurchase of common shares, shares		(210,000)
Repurchase of common shares	(15,207)				(15,207)
Deferral of executive and director compensation	981		981
Deferred Compensation Arrangement with Individual, Shares Issued		57,467
Deferred Compensation Arrangement with Individual, Distribution Paid	0		(2,518)		2,518
Shares Outstanding, Ending Balance at Jun. 30, 2023		27,782,616
Stockholders' Equity, Ending Balance at Jun. 30, 2023	2,298,459	$ 301	350,127	2,057,050	(109,019)
Shares Outstanding, Beginning Balance at Mar. 31, 2023		27,715,616
Stockholders' Equity, Beginning Balance at Mar. 31, 2023	2,183,215	$ 301	349,988	1,939,049	(106,123)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	118,001			118,001
Stock options exercised, shares		277,000
Stock options exercised	10,130		(2,181)		12,311
Stock-based compensation expense	2,301		2,301
Repurchase of common shares, shares		(210,000)
Repurchase of common shares	(15,207)				(15,207)
Deferral of executive and director compensation	19		19
Shares Outstanding, Ending Balance at Jun. 30, 2023		27,782,616
Stockholders' Equity, Ending Balance at Jun. 30, 2023	2,298,459	$ 301	350,127	2,057,050	(109,019)
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	284,807			284,807
Stock options exercised, shares		187,550
Stock options exercised	7,549		(3,623)		11,172
Stock-based compensation expense	7,349		7,349
Repurchase of common shares, shares		(600,000)
Repurchase of common shares	(75,585)				(75,585)
Deferral of executive and director compensation	58		58
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 Jun. 30, 2024		27,403,908
Stockholders' Equity, Ending Balance at Jun. 30, 2024	2,741,117	$ 301	350,554	2,586,155	(195,893)
Shares Outstanding, Beginning Balance at Mar. 31, 2024		27,751,658
Stockholders' Equity, Beginning Balance at Mar. 31, 2024	2,638,785	$ 301	348,039	2,439,409	(148,964)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	146,746			146,746
Stock options exercised, shares		52,250
Stock options exercised	2,054		(1,324)		3,378
Stock-based compensation expense	$ 3,810		3,810
Repurchase of common shares, shares	400,000	(400,000)
Repurchase of common shares	$ (50,307)				(50,307)
Deferral of executive and director compensation	29		29
Shares Outstanding, Ending Balance at Jun. 30, 2024		27,403,908
Stockholders' Equity, Ending Balance at Jun. 30, 2024	$ 2,741,117	$ 301	$ 350,554	$ 2,586,155	$ (195,893)