Stock-Based Compensation - Options Activity (Details) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) shares
Additional disclosures
Intrinsic value of options exercised (in dollars) | $	$ 11,590	$ 832
Proceeds from stock options exercised (in dollars) | $	$ 179
Shares delivered as payment for exercise	362,403	7,930
Stock options exercised in cashless transaction	955,812	71,150
Gross exercise value | $	$ 3,186	$ 104
2016 Plan
Number of shares
Outstanding at beginning of period (in shares)	3,059,690
Granted (in shares)	966,768
Exercised (in shares)	(1,050,448)
Forfeited (in shares)	(18,708)
Outstanding at end of the period (in shares)	2,957,302
Options vested and expected to vest at end of the period (in shares)	2,957,302
Exercisable at end of period (in shares)	1,388,888
Weighted average exercise price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 5.14
Granted (in dollars per share) | $ / shares	14.03
Exercised (in dollars per share) | $ / shares	3.20
Forfeited (in dollars per share) | $ / shares	8.72
Outstanding at end of period (in dollars per share) | $ / shares	8.71
Options vested and expected to vest at end of period (in dollars per share) | $ / shares	8.71
Exercisable at end of period (in dollars per share) | $ / shares	$ 3.29
Weighted average remaining contractual term
Outstanding	7 years 6 months
Options vested and expected to vest at of the period	7 years 6 months
Exercisable	5 years 6 months
Aggregate intrinsic value
Outstanding (in dollars) | $	$ 18,852
Options vested and expected to vest at end of period (in dollars) | $	18,852
Exercisable (in dollars) | $	16,336
Stock options | 2016 Plan
Additional disclosures
Total unrecognized compensation cost (in dollars) | $	$ 10,223
Weighted average period expected to be recognized	3 years 1 month 6 days
Non-employee options | 2016 Plan
Number of shares
Outstanding at end of the period (in shares)	151,048
Additional disclosures
Unvested options (in shares)	766