Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Shares [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Shares [Member]
Shares Outstanding, Beginning Balance at Dec. 31, 2021		28,499,630
Stockholders' Equity, Beginning Balance at Dec. 31, 2021	$ 1,624,184	$ 301	$ 347,452	$ 1,345,321	$ (68,890)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	490,662			490,662
Treasury Stock, Shares, Acquired		(1,200,000)
Treasury Stock, Value, Acquired, Cost Method	(55,334)				(55,334)
Stock options exercised - shares		49,900
Stock options exercised - value	1,366		(810)		2,176
Stock-based compensation expense	8,787		8,787
Deferral of Executive and Director Compensation	1,060		1,060
Deferred Compensation Arrangement with Individual, Shares Issued		90,553
Deferred Compensation Arrangement with Individual, Distribution Paid	0		(3,850)		3,850
Shares Outstanding, Ending Balance at Dec. 31, 2022		27,440,083
Stockholders' Equity, Ending 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	465,365			465,365
Treasury Stock, Shares, Acquired		(726,000)
Treasury Stock, Value, Acquired, Cost Method	(65,344)				(65,344)
Stock options exercised - shares		944,135
Stock options exercised - value	33,795		(10,500)		44,295
Stock-based compensation expense	11,370		11,370
Deferral of Executive and Director Compensation	1,028		1,028
Deferred Compensation Arrangement with Individual, Shares Issued		103,081
Deferred Compensation Arrangement with Individual, Distribution Paid	0		(4,630)		4,630
Shares Outstanding, Ending Balance at Dec. 31, 2023		27,761,299
Stockholders' Equity, Ending 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	$ 563,725			563,725
Treasury Stock, Shares, Acquired	1,200,000	(1,235,000)
Treasury Stock, Value, Acquired, Cost Method	$ (176,953)				(176,953)
Stock options exercised - shares	481,665	481,665
Stock options exercised - value	$ 21,287		(12,744)		34,031
Stock-based compensation expense	14,564		14,564
Deferral of Executive and Director Compensation	115		115
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 Dec. 31, 2024		27,063,023
Stockholders' Equity, Ending Balance at Dec. 31, 2024	$ 2,939,677	$ 301	$ 348,705	$ 2,865,073	$ (274,402)