The Company and Significant Accounting Policies - Summary of Components of AOCI (Detail) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income Loss [Line Items]
Balance, Beginning	$ 250,260	$ 248,237	$ 288,172	$ 302,921	$ 288,172	$ 332,732
Other comprehensive income (loss)	(500)	1,200	(500)
Income tax (expense) benefit		(200)	100
Total other comprehensive income (loss)	(446)	1,000	(400)	50	166	1,048
Balance, Ending	257,540	250,260	248,237	285,976	257,540	285,976
Foreign Currency Translation
Accumulated Other Comprehensive Income Loss [Line Items]
Balance, Beginning	(200)	(700)	(500)		(500)
Other comprehensive income (loss)	(300)	500	(200)
Total other comprehensive income (loss)	(300)	500	(200)
Balance, Ending	(500)	(200)	(700)		(500)
Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Balance, Beginning	700	200	400		400
Other comprehensive income (loss)	(200)	700	(300)
Income tax (expense) benefit		(200)	100
Total other comprehensive income (loss)	(200)	500	(200)
Balance, Ending	500	700	200		500
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Balance, Beginning	481	(520)	(131)	(414)	(131)	(1,412)
Balance, Ending	$ 35	$ 481	$ (520)	$ (364)	$ 35	$ (364)