Earnings Per Share - Computation of Basic and Diluted Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator:
Net income attributable to common stockholders	$ 25,122	$ 32,643	$ 37,849	$ 45,777
Denominator:
Weighted average shares used to compute net income per share attributable to common stockholders, basic (in shares)	105,093	101,969	104,568	101,621
Weighted average effect of potentially dilutive shares to purchase common stock (in shares)	2,254	2,799	2,343	2,873
Weighted average shares used to compute net income per share attributable to common stockholders, diluted (in shares)	107,347	104,768	106,911	104,494
Net income per share available to common stockholders
Basic (in dollars per share)	$ 0.24	$ 0.32	$ 0.36	$ 0.45
Diluted (in dollars per share)	$ 0.23	$ 0.31	$ 0.35	$ 0.44