CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss	Total
Balance at Dec. 31, 2022	$ 734,426	$ 2,236,869	$ (619,862)	$ (3,802)	$ 2,347,631
Balance (in shares) at Dec. 31, 2022	82,593		(31,994)
Increase (Decrease) in Stockholders' Equity
Net Income (loss)		(22,071)			(22,071)
Stock awards	$ 57				57
Stock awards (in shares)	130
Employee income tax paid on stock awards			$ (585)		(585)
Employee income tax paid on stock awards (in shares)			(32)
Sale of common stock under employee stock purchase plan	$ 1,218				1,218
Sale of common stock under employee stock purchase plan (in shares)	78
Stock based compensation expense	$ 4,329				4,329
Treasury stock purchases			$ (100,001)		(100,001)
Treasury stock purchases (in shares)			(5,067)
Net unrealized appreciation (depreciation) on marketable securities, net of taxes				1,480	1,480
Balance at Mar. 31, 2023	$ 740,030	2,214,798	$ (720,448)	(2,322)	2,232,058
Balance (in shares) at Mar. 31, 2023	82,801		(37,093)
Balance at Dec. 31, 2022	$ 734,426	2,236,869	$ (619,862)	(3,802)	2,347,631
Balance (in shares) at Dec. 31, 2022	82,593		(31,994)
Increase (Decrease) in Stockholders' Equity
Net Income (loss)					(6,652)
Net unrealized appreciation (depreciation) on marketable securities, net of taxes					2,994
Balance at Jun. 30, 2023	$ 744,276	2,230,217	$ (816,446)	(808)	2,157,239
Balance (in shares) at Jun. 30, 2023	82,801		(40,428)
Balance at Mar. 31, 2023	$ 740,030	2,214,798	$ (720,448)	(2,322)	2,232,058
Balance (in shares) at Mar. 31, 2023	82,801		(37,093)
Increase (Decrease) in Stockholders' Equity
Net Income (loss)		15,419			15,419
Stock based compensation expense	$ 4,246				4,246
Treasury stock purchases			$ (95,998)		(95,998)
Treasury stock purchases (in shares)			(3,335)
Net unrealized appreciation (depreciation) on marketable securities, net of taxes				1,514	1,514
Balance at Jun. 30, 2023	$ 744,276	2,230,217	$ (816,446)	(808)	2,157,239
Balance (in shares) at Jun. 30, 2023	82,801		(40,428)
Balance at Dec. 31, 2023	$ 754,362	2,271,211	$ (912,396)	325	2,113,502
Balance (in shares) at Dec. 31, 2023	82,840		(42,615)
Increase (Decrease) in Stockholders' Equity
Net Income (loss)		60,298			60,298
Stock awards (in shares)	269
Employee income tax paid on stock awards			$ (6,930)		(6,930)
Employee income tax paid on stock awards (in shares)			(117)
Sale of common stock under employee stock purchase plan	$ 1,446				1,446
Sale of common stock under employee stock purchase plan (in shares)	29
Stock based compensation expense	$ 5,510				5,510
Treasury stock purchases			$ (8,750)		(8,750)
Treasury stock purchases (in shares)			(136)
Net unrealized appreciation (depreciation) on marketable securities, net of taxes				(173)	(173)
Balance at Mar. 31, 2024	$ 761,318	2,331,509	$ (928,076)	152	2,164,903
Balance (in shares) at Mar. 31, 2024	83,138		(42,868)
Balance at Dec. 31, 2023	$ 754,362	2,271,211	$ (912,396)	325	2,113,502
Balance (in shares) at Dec. 31, 2023	82,840		(42,615)
Increase (Decrease) in Stockholders' Equity
Net Income (loss)					135,876
Net unrealized appreciation (depreciation) on marketable securities, net of taxes					(833)
Balance at Jun. 30, 2024	$ 766,130	2,407,087	$ (941,529)	(508)	2,231,180
Balance (in shares) at Jun. 30, 2024	83,139		(43,045)
Balance at Mar. 31, 2024	$ 761,318	2,331,509	$ (928,076)	152	2,164,903
Balance (in shares) at Mar. 31, 2024	83,138		(42,868)
Increase (Decrease) in Stockholders' Equity
Net Income (loss)		75,578			75,578
Stock awards (in shares)	1
Stock based compensation expense	$ 4,812				4,812
Treasury stock purchases			$ (13,453)		(13,453)
Treasury stock purchases (in shares)			(177)
Net unrealized appreciation (depreciation) on marketable securities, net of taxes				(660)	(660)
Balance at Jun. 30, 2024	$ 766,130	$ 2,407,087	$ (941,529)	$ (508)	$ 2,231,180
Balance (in shares) at Jun. 30, 2024	83,139		(43,045)