Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Number of Options
Outstanding, beginning balance (in shares)	3,547,528
Granted (in shares)	56,150	456,550
Exercised (in shares)	(122,926)
Forfeited (in shares)	(32,607)
Expired (in shares)	(414)
Outstanding, ending balance (in shares)	3,447,731		3,547,528
Vested and expected to vest (in shares)	3,473,524
Exercisable (in shares)	2,224,394
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)	28.90
Exercised, weighted average exercise price per share (in dollars per share)	0.94
Forfeited, weighted average exercise price per share (in dollars per share)	11.59
Expired, weighted average exercise price per share (in dollars per share)	8.70
Outstanding, ending balance, weighted average exercise price per share (in dollars per share)	7.44		$ 6.91
Vested and expected to vest, weighted average exercise price per share (in dollars per share)	7.42
Exercisable, weighted average exercise price per share (in dollars per share)	$ 4.14
Weighted Average Remaining Contractual Life and Aggregate Intrinsic Value
Outstanding, weighted average remaining contractual life	6 years 4 months 24 days		6 years 4 months 24 days
Granted, weighted average remaining contractual life	13 years 10 months 24 days
Vested and expected to vest, weighted average remaining contractual life	6 years 4 months 24 days
Exercisable, weighted average remaining contractual life	5 years 4 months 24 days
Outstanding, aggregate intrinsic value	$ 80,355		$ 74,267
Exercised, aggregate intrinsic value	3,310	$ 1,000
Vested and expected to vest, aggregate intrinsic value	81,016
Exercisable, aggregate intrinsic value	$ 59,170