Equity-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Outstanding, Beginning Balance | shares	3,040,214
Number of options, Granted | shares	2,691,157
Number of options, Exercised | shares	(141,759)
Number of options, Forfeited | shares	(884,164)
Number of Options, Outstanding, Ending Balance | shares	4,705,448
Number of Options, Exercisable | shares	1,685,074
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance | $ / shares	$ 8.35
Weighted Average Exercise Price per Share, Granted | $ / shares	16.26
Weighted Average Exercise Price per Share, Exercised | $ / shares	8.16
Weighted Average Exercise Price per Share, Forfeited | $ / shares	12.55
Weighted Average Exercise Price per Share, Outstanding, Ending Balance | $ / shares	12.09
Weighted Average Exercise Price per Share, Exercisable | $ / shares	$ 9.06
Weighted Average Remaining Contractual Term, Outstanding	7 years 7 months 17 days
Weighted Average Remaining Contractual Term, Exercisable	5 years 3 months 3 days
Aggregate Intrinsic Value, Outstanding | $	$ 35,087
Aggregate Intrinsic Value, Exercisable | $	$ 17,172