Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Number of Options
Outstanding, beginning balance (in shares)	3,547,528
Granted (in shares)	237,550	576,300
Exercised (in shares)	(518,421)
Forfeited (in shares)	(74,593)
Expired (in shares)	(862)
Outstanding, ending balance (in shares)	3,191,202		3,547,528
Vested and expected to vest (in shares)	3,212,169
Exercisable (in shares)	1,978,792
Weighted Average Exercise Price per Share
Outstanding, beginning balance, weighted average exercise price per share (in dollars per share)	$ 6.91
Granted, weighted average exercise price per share (in dollars per share)	31.06
Exercised, weighted average exercise price per share (in dollars per share)	2.29
Forfeited, weighted average exercise price per share (in dollars per share)	12.14
Expired, weighted average exercise price per share (in dollars per share)	11.23
Outstanding, ending balance, weighted average exercise price per share (in dollars per share)	9.34		$ 6.91
Vested and expected to vest, weighted average exercise price per share (in dollars per share)	9.31
Exercisable, weighted average exercise price per share (in dollars per share)	$ 4.84
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Outstanding, weighted average remaining contractual life	6 years 6 months		6 years 4 months 24 days
Granted, weighted average remaining contractual life
Vested and expected to vest, weighted average remaining contractual life	6 years 6 months
Exercisable, weighted average remaining contractual life	5 years 6 months
Outstanding, aggregate intrinsic value	$ 90,278		$ 74,267
Exercised, aggregate intrinsic value	15,547	$ 1,500
Vested and expected to vest, aggregate intrinsic value	90,959
Exercisable, aggregate intrinsic value	$ 64,883