Employee Equity-Based Compensation - Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of Shares
Outstanding, beginning balance (shares)	10,132,562	8,090,636
Granted (shares)	1,738,083	3,067,888
Forfeited (shares)	(713,070)	(533,503)
Exercised (shares)	(2,631,935)	(383,319)
Expired (shares)	(480,179)	(109,140)
Outstanding, ending balance (shares)	8,045,461	10,132,562	8,090,636
Exercisable, ending balance (shares)	4,174,813
Weighted Average Exercise Price per Share
Outstanding, beginning balance (dollars per share)	$ 12.28	$ 12.22
Granted (dollars per share)	8.53	14.52
Forfeited (dollars per share)	14.23	20.65
Exercised (dollars per share)	2.30	13.99
Expired (dollars per share)	18.62	23.86
Outstanding, ending balance (dollars per share)	14.18	$ 12.28	$ 12.22
Exercisable, ending balance (dollars per share)	$ 13.89
Cash received from the exercise of options	$ 6,100,000
Tax benefit from share-based compensation	0
Intrinsic value of options exercised	23,500,000	$ 2,300,000	$ 4,600,000
Fair value of shares vesting	$ 9,000,000.0	$ 9,900,000	$ 13,400,000