Employee and Consultant Equity-Based Compensation - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Outstanding, beginning balance (shares)	6,857,124	6,167,170
Granted (shares)	1,208,542	1,024,050
Forfeited (shares)	(79,962)	(147,663)
Exercised (shares)	(656,846)	(158,743)
Expired (shares)	(727)	(27,690)
Outstanding, ending balance (shares)	7,328,131	6,857,124	6,167,170
Exercisable, ending balance (shares)	5,163,899
Weighted Average Exercise Price per Share
Outstanding, beginning balance (dollars per share)	$ 7.72	$ 6.91
Granted (dollars per share)	23.84	14.05
Forfeited (dollars per share)	17.82	18.43
Exercised (dollars per share)	8.93	7.47
Expired (dollars per share)	24.45	4.87
Outstanding, ending balance (dollars per share)	10.16	$ 7.72	$ 6.91
Exercisable, ending balance (dollars per share)	$ 6.38
Cash received from the exercise of options	$ 5,900,000
Tax benefit from share-based compensation	0
Intrinsic value of options exercised	12,100,000	$ 2,200,000	$ 2,000,000
Fair value of shares vesting	$ 12,000,000	$ 6,600,000	$ 7,300,000