Share-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Number of shares
Granted		0
Additional disclosure
Weighted average grant-date fair value per share	$ 5.57
Total fair value of options vested	$ 1,034	$ 0
2014 Equity Incentive Plan
Number of shares
Outstanding at the beginning	3,864,425
Granted	480,919
Outstanding at the end	4,345,344		3,864,425
Options exercisable as of March 31, 2017	2,442,114
Options unvested as of March 31, 2017	1,903,230
Weighted Average Exercise Price
Outstanding at the beginning (in dollars per share)	$ 3.61
Granted (in dollars per share)	9.37
Outstanding at the end (in dollars per share)	4.24		$ 3.61
Options exercisable as of March 31, 2017 (in dollars per share)	3.02
Options unvested as of March 31, 2017 (in dollars per share)	$ 5.81
Additional disclosure
Outstanding average remaining contractual term (in years)	9 years 2 months 5 days		9 years 2 months 16 days
Outstanding aggregate intrinsic value	$ 28,578		$ 15,991
Options exercisable as of March 31, 2017 (in years)	8 years 2 months 1 day
Options unvested as of March 31, 2017 ( in years)	8 years 9 months 26 days
Options exercisable as of March 31, 2017 (in dollars)	$ 19,051
Options unvested as of March 31, 2017 (in dollars)	$ 9,527