Income Taxes - Narrative - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Penalties and interest accrued related to income taxes or uncertain tax positions	$ 0	$ 0
Penalties and interest expense related to income taxes or uncertain tax positions	0	0	$ 0
Liabilities under tax receivable agreement	278,865,000	162,076,000
Investment in partnership	$ 144,688,000	93,089,000
Percent of tax benefits realized that the company must make payments to holders for	85.00%
Named Executive Officers and Members of the Board of Directors
Operating Loss Carryforwards [Line Items]
Liabilities under tax receivable agreement	$ 56,800,000	$ 49,200,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	276,800,000
Operating loss carryforwards expiring in 2037	1,900,000
Operating loss carryforwards expiring in 2038	274,900,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	8,000,000.0
Operating loss carryforwards expiring in 2038	700,000
Operating loss carryforwards expiring in 2028	200,000
Operating loss carryforwards expiring in 2029	1,600,000
Operating loss carryforwards expiring in 2030	$ 5,500,000