Income Taxes - Additional information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017	Jun. 30, 2018 USD ($) Agreement shares	Jun. 30, 2017	Dec. 31, 2017 USD ($)
Tax Credit Carryforward [Line Items]
Effective income tax rate	23.30%	36.40%	23.00%	32.70%
Net deferred tax assets	$ 405,310		$ 405,310		$ 406,153
Total liability related to uncertain tax positions	300		300		2,608
Income tax examination, estimate of possible loss	2,625
Uncertain tax position reserve	2,967		2,967
Uncertain tax position indemnification assets	(2,967)		$ (2,967)
Release of uncertain tax position reserve	$ 342
Number of tax receivable agreements | Agreement			2
Applicable tax savings	85.00%		85.00%
Percentage of remaining tax savings			15.00%
Tax benefit obligation	$ 417,454		$ 417,454		$ 431,360
TRA Holders
Tax Credit Carryforward [Line Items]
Decrease in deferred tax assets			426
Deferred tax asset	9,587		9,587
Deferred tax liability	8,154		$ 8,154
Class A Common Stock
Tax Credit Carryforward [Line Items]
Number of shares exchanged | shares			713,000
Class A Common Stock | TRA Holders
Tax Credit Carryforward [Line Items]
Number of shares exchanged | shares			713,000
Other Expense
Tax Credit Carryforward [Line Items]
Release of indemnification asset	$ 342