CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Balance at Dec. 31, 2020	$ 704,675	$ 2,052,006	$ (617,136)		$ 2,139,545
Balance (in shares) at Dec. 31, 2020	82,095,000		(31,914,000)
Increase (Decrease) in Stockholders' Equity
Net income		111,910			111,910
Exercise of common stock options and vested employee stock awards	$ 606				$ 606
Exercise of common stock options and vested employee stock awards (in shares)	177,000				41,020
Employee income tax paid on vested equity awards			$ (1,576)		$ (1,576)
Employee income tax paid on vested equity awards (in shares)			(42,000)
Sale of common stock under employee stock purchase plan	$ 2,540				2,540
Sale of common stock under employee stock purchase plan (in shares)	64,000
Stock based compensation expense	$ 8,685				8,685
Warrants issued to U.S. Treasury	5,804				5,804
Balance at Dec. 31, 2021	$ 722,310	2,163,916	$ (618,712)		2,267,514
Balance (in shares) at Dec. 31, 2021	82,336,000		(31,956,000)
Increase (Decrease) in Stockholders' Equity
Net income		72,953			72,953
Exercise of common stock options and vested employee stock awards	$ 142				$ 142
Exercise of common stock options and vested employee stock awards (in shares)	151,000				9,817
Employee income tax paid on vested equity awards			$ (1,150)		$ (1,150)
Employee income tax paid on vested equity awards (in shares)			(38,000)
Sale of common stock under employee stock purchase plan	$ 2,815				2,815
Sale of common stock under employee stock purchase plan (in shares)	106,000
Stock based compensation expense	$ 9,159				9,159
Net unrealized appreciation (depreciation) on marketable securities, net of tax				$ (3,802)	(3,802)
Balance at Dec. 31, 2022	$ 734,426	2,236,869	$ (619,862)	(3,802)	2,347,631
Balance (in shares) at Dec. 31, 2022	82,593,000		(31,994,000)
Increase (Decrease) in Stockholders' Equity
Net income		34,342			34,342
Exercise of common stock options and vested employee stock awards	$ 57				$ 57
Exercise of common stock options and vested employee stock awards (in shares)	130,000				3,848
Employee income tax paid on vested equity awards			$ (585)		$ (585)
Employee income tax paid on vested equity awards (in shares)			(32,000)
Sale of common stock under employee stock purchase plan	$ 2,754				2,754
Sale of common stock under employee stock purchase plan (in shares)	117,000
Stock based compensation expense	$ 17,125				17,125
Treasury stock purchases and related excise tax			$ (291,949)		(291,949)
Treasury stock purchases and related excise tax (in shares)			(10,589,000)
Net unrealized appreciation (depreciation) on marketable securities, net of tax				4,127	4,127
Balance at Dec. 31, 2023	$ 754,362	$ 2,271,211	$ (912,396)	$ 325	$ 2,113,502
Balance (in shares) at Dec. 31, 2023	82,840,000		(42,615,000)