CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Total
Beginning Balance (in shares) at Dec. 31, 2020	59,910
Beginning balance at Dec. 31, 2020	$ 28	$ 190,920	$ (2,163)	$ 621,626	$ 810,411
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)	780
Issuance of common stock under employee stock option and stock award plans		1,644			1,644
Repurchase of common stock (in shares)	(878)
Repurchase of common stock	$ (1)	(73,937)			(73,938)
Issuance of common stock under employee stock purchase plan (in shares)	101
Issuance of common stock under employee stock purchase plan	$ 1	6,065			6,066
Stock-based compensation expense related to employee stock options and awards		35,647			35,647
Stock-based compensation expense related to employee stock purchases		1,962			1,962
Payment of dividends to stockholders				(32,599)	(32,599)
Unrealized actuarial gain on pension benefits			967		967
Unrealized gain (loss) on marketable securities			(2,055)		(2,055)
Foreign currency translation adjustment			(486)		(486)
Net income				164,413	164,413
Ending Balance (in shares) at Dec. 31, 2021	59,913
Ending balance at Dec. 31, 2021	$ 28	162,301	(3,737)	753,440	912,032
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)	731
Issuance of common stock under employee stock option and stock award plans		257			257
Repurchase of common stock (in shares)	(3,770)
Repurchase of common stock	$ (4)	(190,827)		(120,263)	(311,094)
Issuance of common stock under employee stock purchase plan (in shares)	87
Issuance of common stock under employee stock purchase plan		5,905			5,905
Stock-based compensation expense related to employee stock options and awards		20,494			20,494
Stock-based compensation expense related to employee stock purchases		1,870			1,870
Payment of dividends to stockholders				(41,492)	(41,492)
Unrealized actuarial gain on pension benefits			1,536		1,536
Unrealized gain (loss) on marketable securities			(4,158)		(4,158)
Foreign currency translation adjustment			(985)		(985)
Net income				170,851	170,851
Ending Balance (in shares) at Dec. 31, 2022	56,961
Ending balance at Dec. 31, 2022	$ 24		(7,344)	762,536	755,216
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock award plans (in shares)	476
Repurchase of common stock (in shares)	(784)
Repurchase of common stock	$ (1)	(34,765)		(20,583)	(55,349)
Issuance of common stock under employee stock purchase plan (in shares)	85
Issuance of common stock under employee stock purchase plan		6,237			6,237
Stock-based compensation expense related to employee stock options and awards		26,624			26,624
Stock-based compensation expense related to employee stock purchases		$ 1,904			1,904
Payment of dividends to stockholders				(44,008)	(44,008)
Unrealized actuarial gain on pension benefits			723		723
Unrealized gain (loss) on marketable securities			5,579		5,579
Foreign currency translation adjustment			(420)		(420)
Net income				55,735	55,735
Ending Balance (in shares) at Dec. 31, 2023	56,738
Ending balance at Dec. 31, 2023	$ 23		$ (1,462)	$ 753,680	$ 752,241