Income Taxes (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 17, 2018 agreement	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Operating Loss Carryforwards [Line Items]
Effective combined income tax rate				15.80%	15.50%
Income tax (benefit) expense		$ (9,972)	$ 4,004	$ (21,074)	$ 17,147
NOL carryback refund		9,300		9,300
Number of tax receivable agreements | agreement	2
Taxes payable		47,500		47,500		$ 50,300
Deferred tax asset		55,000		55,000		49,900
Taxes payable, current		0		0		1,800
Taxes payable, noncurrent		47,512		47,512		$ 48,481
Tax Receivable Agreement
Operating Loss Carryforwards [Line Items]
NOL carryback refund		5,400		5,400
Payment for tax benefit				2,000
Shares of Class B Common Stock | Tax Receivable Agreement | Common Stock
Operating Loss Carryforwards [Line Items]
Taxes payable		4,400	25,300	4,400	25,300
Deferred tax asset		$ 5,200	$ 29,800	$ 5,200	$ 29,800