Net Income (Loss) per Share - Schedule of Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Net income (loss) attributable to common stockholders, basic and diluted	$ 1,291	$ 21,417	$ (14,048)	$ 39,193
Denominator:
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, basic	83,884	83,257	83,605	82,447
Dilutive effect of stock options	2,455	10,333		11,023
Dilutive effect of restricted stock units	30	274		263
Weighted-average shares used to compute net income (loss) per share attributable to common stockholders, diluted	86,369	93,864	83,605	93,733
Net income (loss) per share attributable to common stockholders:
Basic	$ 0.02	$ 0.26	$ (0.17)	$ 0.48
Diluted	$ 0.01	$ 0.23	$ (0.17)	$ 0.42