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
	Mar. 31, 2018	Mar. 31, 2017
Numerator:
Net income available to common stockholders	$ 28,032	$ 9,882
Denominator:
Weighted average shares used to compute net income per share attributable to common stockholders, basic (in shares)	107,449	104,038
Weighted average effect of potentially dilutive shares to purchase common stock (in shares)	3,332	2,431
Weighted average shares used to compute net income per share attributable to common stockholders, diluted (in shares)	110,781	106,469
Net income per share available to common stockholders
Basic (in dollars per share)	$ 0.26	$ 0.09
Diluted (in dollars per share)	$ 0.25	$ 0.09