Equity-Based Compensation - Additional Information (Details) - shares	Dec. 31, 2020	Sep. 30, 2020	Sep. 30, 2018	May 31, 2018
2018 Equity Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant under the plan (shares)	115,139			3,500,000
Additional Class A common shares added at the beginning of calendar year as percentage of common stock outstanding at end of previous year (percent)			4.00%
A2020 Equity Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant under the plan (shares)	985,000	1,500,000