Stockholders' Equity - Components of Stockholders' Equity (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Beginning Balance		$ 210,099	$ 201,502	$ 203,907	$ 185,766
Issuance of common stock under stock plans, including tax effects		(499)	2,023	1,323	4,493
Repurchases of common stock			$ (7,973)	$ (15,112)	$ (10,646)
Repurchases of common stock, Shares			200,000	300,000	200,000
Stock-based compensation expense		3,905	$ 2,462	$ 11,036	$ 7,351
Accounting Standards Update [Extensible List]				us-gaap:AccountingStandardsUpdate201613Member
Net income		5,414	4,522	$ 23,436	16,821
Net change in interest rate swap, net of tax		(5)	128	259	457
Net change in marketable investments, net of tax		(54)	(4)	(147)	(4)
Foreign currency translation		(4,971)	(1,508)	(10,813)	(3,086)
Ending Balance		213,889	201,152	213,889	201,152
Common Stock [Member]
Beginning Balance		$ 242	$ 238	$ 241	$ 236
Beginning Balance, Shares		24,159,000	23,780,000	24,085,000	23,648,000
Issuance of common stock under stock plans, including tax effects		$ 2	$ 2	$ 3	$ 4
Issuance of common stock under,stock plans including tax effects, Shares		193,000	262,000	267,000	394,000
Ending Balance		$ 244	$ 240	$ 244	$ 240
Ending Balance, Shares		24,352,000	24,042,000	24,352,000	24,042,000
Additional Paid-in Capital [Member]
Beginning Balance		$ 254,937	$ 237,485	$ 245,985	$ 230,128
Issuance of common stock under stock plans, including tax effects		(501)	2,021	1,320	4,489
Stock-based compensation expense		3,905	2,462	11,036	7,351
Ending Balance		258,341	241,968	258,341	241,968
Retained Earnings [Member]
Beginning Balance		170,847	140,280	152,825	127,981
Net income		5,414	4,522	23,436	16,821
Ending Balance		176,261	144,802	176,261	144,802
Treasury Stock [Member]
Beginning Balance		$ (207,067)	$ (174,562)	$ (191,955)	$ (171,889)
Beginning Balance, Shares		5,305,000	4,694,000	5,027,000	4,631,000
Repurchases of common stock			$ (7,973)	$ (15,112)	$ (10,646)
Repurchases of common stock, Shares			170,000	278,000	233,000
Ending Balance		$ (207,067)	$ (182,535)	$ (207,067)	$ (182,535)
Ending Balance, Shares		5,305,000	4,864,000	5,305,000	4,864,000
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance		$ (8,860)	$ (1,939)	$ (3,189)	$ (690)
Net change in interest rate swap, net of tax		(5)	128	259	457
Net change in marketable investments, net of tax		(54)	(4)	(147)	(4)
Foreign currency translation	[1]	(4,971)	(1,508)	(10,813)	(3,086)
Ending Balance		$ (13,890)	$ (3,323)	$ (13,890)	$ (3,323)

[1] The Company does not record tax provisions or benefits for the net changes in foreign currency translation adjustments as it intends to permanently reinvest undistributed earnings of its foreign subsidiaries.