Share-Based Compensation - Stock Option Activity (Details)	9 Months Ended
	Sep. 30, 2021 $ / shares shares	Dec. 31, 2020 $ / shares shares
Options
Outstanding at beginning of period (in shares) | shares	6,220,971
Granted (in shares) | shares	4,775
Exercised (in shares) | shares	(1,108,632)
Canceled/forfeited (in shares) | shares	(10,888)
Expired (in shares) | shares	(7,000)
Outstanding at end of period (in shares) | shares	5,099,226
Outstanding, vested and exercisable at end of period (in shares) | shares	5,069,288	5,230,690
Weighted- Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 3.68
Granted (in dollars per share) | $ / shares	23.60
Exercised (in dollars per share) | $ / shares	4.90
Canceled/forfeited (in dollars per share) | $ / shares	6.02
Expired (in dollars per share) | $ / shares	27.08
Outstanding at end of period (in dollars per share) | $ / shares	3.40
Outstanding, vested and exercisable at end of period (in dollars per share) | $ / shares	$ 3.35	$ 3.73