Income Taxes - Additional information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018	Jun. 30, 2019 USD ($) agreement shares	Jun. 30, 2018	Dec. 31, 2018 USD ($)
Tax Credit Carryforward [Line Items]
Effective income tax rate	22.20%	23.30%	18.90%	23.00%
Net deferred tax assets	$ 423,773		$ 423,773		$ 412,538
Total liability related to uncertain tax positions	430		$ 430		300
Number of tax receivable agreements | agreement			2
Percentage of remaining tax savings			15.00%
Tax benefit obligation	$ 433,605		$ 433,605		$ 429,233
TRA Holders
Tax Credit Carryforward [Line Items]
Applicable tax savings	85.00%		85.00%
Decrease in deferred tax assets			$ 639
Deferred tax asset	$ 20,040		20,040
Deferred tax liability	$ 17,016		$ 17,016
Class A Common Stock
Tax Credit Carryforward [Line Items]
Number of shares exchanged | shares			865,810
Class A Common Stock | TRA Holders
Tax Credit Carryforward [Line Items]
Number of shares exchanged | shares			865,810