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, 2021	$ 722,310	$ 2,163,916	$ (618,712)		$ 2,267,514
Balance (in shares) at Dec. 31, 2021	82,336		(31,956)
Increase (Decrease) in Stockholders' Equity
Net income		17,734			17,734
Exercise of common stock options and vested employee stock awards	$ 27				27
Exercise of common stock options and vested employee stock awards (in shares)	139
Employee income tax paid on vested equity awards			$ (1,123)		(1,123)
Employee income tax paid on vested equity awards (in shares)			(37)
Sale of common stock under employee stock purchase plan	$ 1,487				1,487
Sale of common stock under employee stock purchase plan (in shares)	40
Stock based compensation expense	$ 4,076				4,076
Balance at Mar. 31, 2022	$ 727,900	2,181,650	$ (619,835)		2,289,715
Balance (in shares) at Mar. 31, 2022	82,515		(31,993)
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		(22,071)			(22,071)
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
Employee income tax paid on vested equity awards			$ (585)		(585)
Employee income tax paid on vested equity 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 on marketable securities, net of tax				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)