Stock-Based Compensation - Restricted Stock (Details) - Restricted stock awards
3 Months Ended
Mar. 31, 2021
$ / shares
shares
Awards  
Unvested balance, beginning of period (in shares) | shares 12,093,723
Granted (in shares) | shares 0
Vested (in shares) | shares (424,290)
Forfeited (in shares) | shares (1,457)
Unvested balance, end of period (in shares) | shares 11,667,976
Weighted Average Grant-Date Fair Value  
Beginning of period (in dollars per share) | $ / shares $ 2.33
Granted (in dollars per share) | $ / shares 0
Vested (in dollars per share) | $ / shares 6.21
Forfeited (in dollar per share) | $ / shares 14.28
End of period (in dollars per share) | $ / shares $ 2.18
Officer and employees  
Weighted Average Grant-Date Fair Value  
Vesting period 3 years
Director  
Weighted Average Grant-Date Fair Value  
Vesting period 1 year