Employee Benefit Plans - Restricted Stock Activity (Details) - Restricted stock - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Benefit Plans
Compensation cost	$ 7,600	$ 2,800	$ 966
Unrecognized compensation cost	$ 41,500	$ 8,400	$ 3,900
Period for recognition	3 years
Shares
Unvested restricted stock, beginning balance (in shares)	4,608,560
Granted (in shares)	3,227,149
Vested (in shares)	(1,896,901)
Forfeited (in shares)	(64,166)
Unvested restricted stock, end balance (in shares)	5,874,642	4,608,560
Aggregate Intrinsic Value
Unvested restricted stock, end balance, aggregate intrinsic value	$ 199,209
Minimum
Employee Benefit Plans
Vesting period	1 year
Maximum
Employee Benefit Plans
Vesting period	3 years