The Company and Significant Accounting Policies - Summary of Components of AOCI (Detail) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive income (loss)	$ (400)	$ (600)	$ (1,412)		$ (1,412)
Other comprehensive income (loss)	100	400	1,000
Income tax (expense) benefit	(100)	(200)	(200)
Total other comprehensive income (loss)	50	200	800	$ 143	1,048	$ (1,359)
Accumulated other comprehensive income (loss)	(364)	(400)	(600)		(364)
Foreign Currency Translation
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive income (loss)	(700)	(400)	(400)		(400)
Other comprehensive income (loss)	(100)	(300)
Total other comprehensive income (loss)	(100)	(300)
Accumulated other comprehensive income (loss)	(800)	(700)	(400)		(800)
Marketable Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Accumulated other comprehensive income (loss)	300	(200)	(1,000)		(1,000)
Other comprehensive income (loss)	200	700	1,000
Income tax (expense) benefit	(100)	(200)	(200)
Total other comprehensive income (loss)	100	500	800
Accumulated other comprehensive income (loss)	$ 400	$ 300	$ (200)		$ 400