Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Member Units [Member]	Common Stock Class A	Common Stock Class B	Common Stock Class C	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Noncontrolling Interest
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest	$ 284,694	$ 285,301						$ (607)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31,368	31,368
Equity-based compensation expense	4,969	4,969
Foreign currency translation adjustment	(86)
Distribution Made to Limited Liability Company (LLC) Member, Cash Distributions Declared	(28,110)	(28,110)
Adjustments Related to Tax Withholding for Share-based Compensation	290	290
Net Settlement Of Outstanding Vested Options	(744)	(744)
Net Settlement, Issuance of Membership Units	744	744
Stockholders' Equity, Repurchase of Options and Units	(15,148)	(15,148)
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	966	966
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	(86)							(86)
Limited Liability Company (LLC) Members' Equity, Including Portion Attributable to Noncontrolling Interest	278,363	$ 279,056						(693)
Net income	(8,580)
Dividends declared							$ (500)
Exchanges of non-controlling interest for Class A common stock (in shares)			(19,088,000)
Foreign currency translation adjustment	908
Balance (in shares) at Dec. 31, 2017			35,937,500	173,624,316	42,944,647
Balance at Dec. 31, 2017	742,133		$ 36	$ 174	$ 43	$ 107,008	1,602	31	$ 633,239
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	29,318						4,052		25,266
Distributions to non-controlling interest	(11,617)								(11,617)
Dividends declared	(2,961)						(2,961)
Equity-based compensation expense	35,733					13,057			22,676
Issuance of Class A common stock upon settlement of restricted stock unit awards, net of shares withheld for tax (in shares)			131,000
Issuance of Class A common stock upon settlement of restricted stock unit awards, net of shares withheld for tax	(1,232)		$ 0			(1,232)
Issuance of restricted stock awards (in shares)			61,000
Issuance of restricted stock awards	0
Exchanges of non-controlling interest for Class A common stock (in shares)			19,088,000
Exchanges of non-controlling interest for Class A common stock	0		$ 19	$ (19)		53,403			(53,403)
Repurchase of common units and cancellation of Class B common stock (in shares)				(6,055,000)
Repurchase of common units and cancellation of Class B common stock	60,644			$ 6		9,085			51,553
Tax Receivable Agreement, Recognition Resulting From Exchange Of Noncontrolling Interest For Common Stock	52,535					52,535
Net deferred tax assets resulting from exchanges of non-controlling interest for Class A common stock	29,512					29,512
Adjustments To Additional Paid-In Capital, Settlement Of Option Loans	(314)					(63)			(251)
Foreign currency translation adjustment	331							48	283
Balance (in shares) at Dec. 31, 2018			55,217,682	148,480,538	42,944,647
Balance at Dec. 31, 2018	$ 708,352		$ 55	$ 149	$ 43	$ 140,191	$ 2,693	$ 79	$ 565,142