Equity-Based Compensation - Stock options (Details) - Stock options $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($) $ / shares shares
Number of Shares
Granted (in shares) | shares	1,509,705
Exercised (in shares) | shares	(449)
Forfeited (in shares) | shares	(8,525)
Outstanding, end (in shares) | shares	1,500,731
Outstanding exercisable, end (in shares) | shares	119,066
Weighted Average Exercise Price
Granted (in dollars per share)	$ 9.64
Exercised (in dollars per share)	5.77
Forfeited (in dollars per share)	7.73
Outstanding, end (in dollars per share)	9.65
Outstanding exercisable, end (in dollars per share)	$ 8.73
Stock options
Weighted average remaining contractual term	9 years 6 months 7 days
Aggregate intrinsic value | $	$ 24,157
Weighted average remaining contractual term, exercisable	9 years 5 months 19 days
Aggregate intrinsic value, exercisable | $	$ 2,017
Weighted average fair value of options granted	$ 6.81