Employee Equity-Based Compensation - Narrative (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Compensation expense related to unvested stock options	$ 7.2
RSUs
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Compensation expense related to unvested RSUs	$ 15.2
Performance-based stock options
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Contractual life	10 years
Granted (shares)	45,000	105,000
Vested (shares)		45,000
Performance-based stock options | Minimum
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Vesting period	1 year
Expected term of award	5 years
Performance-based stock options | Maximum
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Vesting period	2 years
Expected term of award	7 years
Performance-based RSUs
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Contractual life	10 years
Performance-based RSUs | 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Granted (shares)		364,338
Vested (shares)	84,000	81,000
Forfeited (shares)	9,369	33,364
Outstanding (shares)	165,974
Performance-based RSUs | 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Granted (shares)	233,472
Forfeited (shares)	10,755
Outstanding (shares)	222,717
Performance-based RSUs | Minimum
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Vesting period	1 year
Performance-based RSUs | Maximum
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Vesting period	3 years