Stockholders' Equity - Components of Stockholders' Equity (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Beginning Balance		$ 202,430	$ 192,237	$ 203,907	$ 185,766
Issuance of common stock under stock plans, including tax effects		100	336	1,822	2,470
Repurchases of common stock		$ (5,653)	$ (2,673)	$ (15,112)	$ (2,673)
Repurchases of common stock, Shares		100,000	100,000	300,000	100,000
Stock-based compensation expense		$ 3,837	$ 2,397	$ 7,131	$ 4,889
Accounting Standards Update [Extensible List]				us-gaap:AccountingStandardsUpdate201613Member
Net income		13,874	8,343	$ 18,022	12,299
Net change in interest rate swap, net of tax		68	139	264	329
Net change in marketable investments, net of tax		(29)		(93)
Foreign currency translation		(4,528)	723	(5,842)	(1,578)
Ending Balance		210,099	201,502	210,099	201,502
Common Stock [Member]
Beginning Balance		$ 241	$ 238	$ 241	$ 236
Beginning Balance, Shares		24,143,000	23,755,000	24,085,000	23,648,000
Issuance of common stock under stock plans, including tax effects		$ 1		$ 1	$ 2
Issuance of common stock under,stock plans including tax effects, Shares		16,000	25,000	74,000	132,000
Ending Balance		$ 242	$ 238	$ 242	$ 238
Ending Balance, Shares		24,159,000	23,780,000	24,159,000	23,780,000
Additional Paid-in Capital [Member]
Beginning Balance		$ 251,001	$ 234,752	$ 245,985	$ 230,128
Issuance of common stock under stock plans, including tax effects		99	336	1,821	2,468
Stock-based compensation expense		3,837	2,397	7,131	4,889
Ending Balance		254,937	237,485	254,937	237,485
Retained Earnings [Member]
Beginning Balance		156,973	131,937	152,825	127,981
Net income		13,874	8,343	18,022	12,299
Ending Balance		170,847	140,280	170,847	140,280
Treasury Stock [Member]
Beginning Balance		$ (201,414)	$ (171,889)	$ (191,955)	$ (171,889)
Beginning Balance, Shares		5,202,000	4,631,000	5,027,000	4,631,000
Repurchases of common stock		$ (5,653)	$ (2,673)	$ (15,112)	$ (2,673)
Repurchases of common stock, Shares		103,000	63,000	278,000	63,000
Ending Balance		$ (207,067)	$ (174,562)	$ (207,067)	$ (174,562)
Ending Balance, Shares		5,305,000	4,694,000	5,305,000	4,694,000
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance		$ (4,371)	$ (2,801)	$ (3,189)	$ (690)
Net change in interest rate swap, net of tax		68	139	264	329
Net change in marketable investments, net of tax		(29)		(93)
Foreign currency translation	[1]	(4,528)	723	(5,842)	(1,578)
Ending Balance		$ (8,860)	$ (1,939)	$ (8,860)	$ (1,939)

[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.