The Company and Significant Accounting Policies - Reconciliation of Basic and Diluted Income (Loss) Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share Basic And Diluted [Abstract]
Net income (loss)	$ (16,279)	$ 1,424	$ 4,840	$ (1,808)	$ (14,855)	$ 3,033
Denominator:
Weighted average common shares outstanding, basic	85,359,998		88,959,935		85,728,820	89,635,759
Basic earnings per share:
Net income (loss) per share	$ (0.19)		$ 0.05		$ (0.17)	$ 0.03
Denominator:
Weighted average common shares outstanding, basic	85,359,998		88,959,935		85,728,820	89,635,759
Dilutive securities:
Stock options and restricted stock units			1,062,014			1,169,327
Weighted average common shares outstanding, diluted	85,359,998		90,021,949		85,728,820	90,805,086
Diluted earnings per share:
Net income (loss) per share	$ (0.19)		$ 0.05		$ (0.17)	$ 0.03