Net Income Per Share Available to Common Stock - Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Calculation of Basic and Diluted Net Income Per Share, Numerator [Abstract]
Net income	$ 58,783	$ 51,257	$ 38,904	$ 35,245	$ 43,924	$ 28,690	$ 23,996	$ 24,492	$ 184,189	$ 121,102	$ 86,850
Less: undistributed earnings allocated to participating securities									(1,224)	(1,987)	(17,961)
Net income attributable to common stockholders, basic									182,965	119,115	68,889
Add: undistributed earnings allocated to participating securities									74	149	1,635
Net income attributable to common stockholders, diluted									$ 183,039	$ 119,264	$ 70,524
Calculation of Basic and Diluted Net Income Per Share, Denominator [Abstract]
Weighted-average shares used in computing net income per share available to common stockholders, basic (in shares)									68,771	65,964	48,427
Add weighted-average effect of dilutive securities:
Stock options, RSUs and RSAs (in shares)									4,408	5,363	6,059
Employee stock purchase plan (in shares)									43	84	104
Stock purchase rights (in shares)									0	0	0
Weighted-average shares used in computing net income per share available to common stockholders, diluted (in shares)									73,222	71,411	54,590
Net income per share attributable to common stockholders:
Basic (in dollars per share)	$ 0.84	$ 0.74	$ 0.57	$ 0.52	$ 0.65	$ 0.42	$ 0.36	$ 0.37	$ 2.66	$ 1.81	$ 1.42
Diluted (in dollars per share)	$ 0.79	$ 0.69	$ 0.53	$ 0.48	$ 0.60	$ 0.39	$ 0.33	$ 0.34	$ 2.50	$ 1.67	$ 1.29