Employee Equity-Based Compensation - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Number of Shares
Outstanding, beginning balance (shares) | shares	7,328,131
Granted (shares) | shares	920,439
Forfeited (shares) | shares	(120,212)
Exercised (shares) | shares	(44,290)
Expired (shares) | shares	(352)
Outstanding, ending balance (shares) | shares	8,083,716
Weighted Average Exercise Price per Share
Outstanding, beginning balance (dollars per share) | $ / shares	$ 10.16
Granted (dollars per share) | $ / shares	26.08
Forfeited (dollars per share) | $ / shares	9.25
Exercised (dollars per share) | $ / shares	18.31
Expired (dollars per share) | $ / shares	24.45
Outstanding, ending balance (dollars per share) | $ / shares	$ 11.94