Net Income Per Share (Detail) - Basic and Diluted Net Income Per Share Available To Common Stockholders - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income	$ 80	$ 5,655
Basic shares:
Weighted-average shares used in computing basic net income per share	49,755	48,676
Diluted shares:
Dilutive effect of stock options and restricted stock units using the treasury-stock method	512	629
Weighted-average shares used in computing diluted net income per share	50,267	49,305
Net income per share:
Basic (dollars per common share)	$ 0.00	$ 0.12
Diluted (dollars per common share)	$ 0.00	$ 0.11