Stockholders' Equity - Components of Stockholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Beginning Balance	$ 173,409	$ 149,686	$ 158,088	$ 151,600
Issuance of common stock under stock plans, net	(420)	(793)	638	3,357
Stock-based compensation expense	2,697	3,072	$ 7,964	8,605
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member
Net income (loss)	(3,760)	(2,699)	$ 7,564	(14,460)
Other comprehensive income (loss)	2,782	(1,614)	611	(1,450)
Ending Balance	174,708	147,652	174,708	147,652
Cumulative Effect Adjustment [Member]
Beginning Balance			(157)
Common Stock [Member]
Beginning Balance	$ 234	$ 231	$ 233	$ 230
Beginning Balance, Shares	23,401,000	23,089,000	23,275,000	22,951,000
Issuance of common stock under stock plans, net	$ 2	$ 1	$ 3	$ 2
Issuance of common stock under stock plans, net, Shares	178,000	158,000	304,000	296,000
Ending Balance	$ 236	$ 232	$ 236	$ 232
Ending Balance, Shares	23,579,000	23,247,000	23,579,000	23,247,000
Additional Paid-in Capital [Member]
Beginning Balance	$ 222,778	$ 210,378	$ 216,454	$ 200,696
Issuance of common stock under stock plans, net	(422)	(794)	635	3,355
Stock-based compensation expense	2,697	3,072	7,964	8,605
Ending Balance	225,053	212,656	225,053	212,656
Retained Earnings [Member]
Beginning Balance	129,314	115,956	118,147	127,717
Net income (loss)	(3,760)	(2,699)	7,564	(14,460)
Ending Balance	125,554	113,257	125,554	113,257
Retained Earnings [Member] | Cumulative Effect Adjustment [Member]
Beginning Balance			(157)
Treasury Stock [Member]
Beginning Balance	$ (171,889)	$ (171,889)	$ (171,889)	$ (171,889)
Beginning Balance, Shares	4,631,000	4,631,000	4,631,000	4,631,000
Ending Balance	$ (171,889)	$ (171,889)	$ (171,889)	$ (171,889)
Ending Balance, Shares	4,631,000	4,631,000	4,631,000	4,631,000
Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance	$ (7,028)	$ (4,990)	$ (4,857)	$ (5,154)
Other comprehensive income (loss)	2,782	(1,614)	611	(1,450)
Ending Balance	$ (4,246)	$ (6,604)	$ (4,246)	$ (6,604)