Stock-Based Compensation Expense and Employee Benefit Plans - Unvested Restricted Stock Unit Activity (Details) - Restricted Stock Units	6 Months Ended
	Jun. 30, 2021 $ / shares shares
Unvested Restricted Stock Unit Activity
Unvested balance (in shares) | shares	6,418,788
Granted (in shares) | shares	5,147,861
Vested (in shares) | shares	(1,951,664)
Forfeited (in shares) | shares	(745,708)
Unvested balance (in shares) | shares	8,869,277
Weighted Average Grant Date Fair Value
Unvested balance (in dollars per share) | $ / shares	$ 13.71
Granted (in dollars per share) | $ / shares	24.56
Vested (in dollars per share) | $ / shares	16.94
Forfeited (in dollars per share) | $ / shares	13.43
Unvested balance (in dollars per share) | $ / shares	$ 19.32