Stock-based Compensation - Stock Option Plan Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Outstanding Shares
Beginning balance (in shares)	7,527,680
Granted (in shares)	338,725
Exercised (in shares)	(2,364,523)
Canceled (in shares)	(347,573)
Ending balance (in shares)	5,154,309	7,527,680
Vested and expected to vest (in shares)	4,852,064
Exercisable (in shares)	3,458,555
Weighted Average Exercise Price
Weighted average exercise price, Beginning balance (in dollars per share)	$ 19.25
Weighted average exercise price, granted (in dollars per share)	38.40
Weighted average exercise price, exercised (in dollars per share)	10.38
Weighted average exercise price, canceled (in dollars per share)	33.72
Weighted average exercise price, Ending balance (in dollars per share)	23.60	$ 19.25
Weighted average exercise price, Vested and expected to vest (in dollars per share)	23.05
Weighted average exercise price, Exercisable (in dollars per share)	$ 19.94
Weighted Average Remaining Contractual Life
Weighted average remaining contractual life (in years)	6 years 7 months 6 days	6 years 12 days
Weighted average remaining contractual life, Vested and expected to vest (in years)	6 years 6 months
Weighted average remaining contractual life, Exercisable (in years)	5 years 7 months 6 days
Aggregate Intrinsic Value
Aggregate intrinsic value	$ 145,402	$ 101,717
Aggregate intrinsic value, Vested and expected to vest	139,543
Aggregate intrinsic value, Exercisable	$ 110,203