Condensed Consolidated Statements of Changes in Equity (Unaudited) - USD ($) $ in Thousands	Total	Additional Paid in Capital	Retained Earnings	Total Stockholders’ Equity	Non-controlling Interest	Shares of Class A Common Stock	Shares of Class A Common Stock Common Stock	Shares of Class B Common Stock	Shares of Class B Common Stock Common Stock
Beginning balance at Dec. 31, 2018	$ 740,814	$ 312,659	$ 119,274	$ 433,069	$ 307,745		$ 684		$ 452
Beginning balance (in shares) at Dec. 31, 2018							68,360,000		45,207,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchanges of Class B Common Stock for Class A Common Stock (shares)							8,551,000		(8,551,000)
Exchange of Class B Common Stock for Class A Common Stock	0	64,065		64,065	(64,065)		$ 85		$ (85)
Offering Costs	(1,499)	(1,001)		(1,001)	(498)
Effect of exchange on deferred tax asset, net of liability under tax receivable agreements	4,466	4,466		4,466
Deferred tax impact of ownership changes from exchanges and repurchases	(7,148)	(7,148)		(7,148)	0
Class A Common Stock dividend	(10,978)		(10,978)	(10,978)
Distributions to non-controlling unitholders	(6,215)				(6,215)
Other distributions and advance payments to non-controlling interest unitholders	(1,104)				(1,104)
Share repurchase (shares)							(1,303,000)
Share repurchases	(17,098)	(13,017)		(13,030)	(4,068)		$ (13)
Stock based compensation expense	9,993	8,802		8,802	1,191
Vesting of restricted stock units (shares)							268,000
Vesting of restricted stock units	(1,039)	(302)		(299)	(740)		$ 3
Restricted stock and RSU forfeitures (shares)							(8,000)
Restricted stock and RSU forfeitures	1	(22)	1	(21)	22		$ 0
Net (loss) income	93,272		51,151	51,151	42,121
Ending balance (in shares) at Sep. 30, 2019							75,868,000		36,656,000
Ending balance at Sep. 30, 2019	803,465	368,502	159,448	529,076	274,389		$ 759		$ 367
Beginning balance at Jun. 30, 2019	792,446	318,099	152,322	471,547	320,899		$ 690		$ 436
Beginning balance (in shares) at Jun. 30, 2019							68,962,000		43,570,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchanges of Class B Common Stock for Class A Common Stock (shares)							6,914,000		(6,914,000)
Exchange of Class B Common Stock for Class A Common Stock	0	52,652		52,652	(52,652)		$ 69		$ (69)
Offering Costs	(1,499)	(1,001)		(1,001)	(498)
Effect of exchange on deferred tax asset, net of liability under tax receivable agreements	3,570	3,570		3,570
Deferred tax impact of ownership changes from exchanges and repurchases	(7,148)	(7,148)		(7,148)	0
Class A Common Stock dividend	(3,871)		(3,871)	(3,871)
Distributions to non-controlling unitholders	(1,857)				(1,857)
Other distributions and advance payments to non-controlling interest unitholders	(557)				(557)
Stock based compensation expense	3,542	2,351		2,351	1,191
Vesting of restricted stock units (shares)							0
Vesting of restricted stock units	0	1		1	(1)		$ 0
Restricted stock and RSU forfeitures (shares)							(8,000)
Restricted stock and RSU forfeitures	(1)	(22)	(1)	(23)	22		$ 0
Net (loss) income	18,840		10,998	10,998	7,842
Ending balance (in shares) at Sep. 30, 2019							75,868,000		36,656,000
Ending balance at Sep. 30, 2019	803,465	368,502	159,448	529,076	274,389		$ 759		$ 367
Beginning balance at Dec. 31, 2019	781,492	410,596	143,105	554,827	226,665		$ 819		$ 307
Beginning balance (in shares) at Dec. 31, 2019						81,885,384	81,885,000	30,638,960	30,639,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchanges of Class B Common Stock for Class A Common Stock (shares)							3,571,000		(3,571,000)
Exchange of Class B Common Stock for Class A Common Stock	0	24,762		24,762	(24,762)		$ 36		$ (36)
Effect of exchange on deferred tax asset, net of liability under tax receivable agreements	778	778		778
Class A Common Stock dividend	(4,244)		(4,244)	(4,244)
Distributions to non-controlling unitholders	(1,532)				(1,532)
Other distributions and advance payments to non-controlling interest unitholders	(256)	(1)		(1)	(255)
Stock based compensation expense	12,894	9,557		9,557	3,337
Vesting of restricted stock units (shares)							414,000
Vesting of restricted stock units	(402)	472		477	(879)		$ 5
Restricted stock and RSU forfeitures (shares)							(4,000)
Restricted stock and RSU forfeitures	8	(9)	9	(1)	9		$ (1)
Net (loss) income	(112,443)		(78,553)	(78,553)	(33,890)
Ending balance (in shares) at Sep. 30, 2020						85,866,440	85,866,000	27,067,247	27,068,000
Ending balance at Sep. 30, 2020	676,295	446,155	60,317	507,602	168,693		$ 859		$ 271
Beginning balance at Jun. 30, 2020	719,957	435,885	94,817	531,831	188,126		$ 848		$ 281
Beginning balance (in shares) at Jun. 30, 2020							84,853,000		28,081,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchanges of Class B Common Stock for Class A Common Stock (shares)							1,013,000		(1,013,000)
Exchange of Class B Common Stock for Class A Common Stock	0	6,561		6,561	(6,561)		$ 10		$ (10)
Effect of exchange on deferred tax asset, net of liability under tax receivable agreements	324	324		324
Other distributions and advance payments to non-controlling interest unitholders	549	0		0	549
Stock based compensation expense	4,487	3,385		3,385	1,102
Vesting of restricted stock units (shares)							0
Vesting of restricted stock units	1	0		1	0		$ 1
Restricted stock and RSU forfeitures (shares)							0
Restricted stock and RSU forfeitures	2	0	2	2	0		$ 0
Net (loss) income	(49,025)		(34,502)	(34,502)	(14,523)
Ending balance (in shares) at Sep. 30, 2020						85,866,440	85,866,000	27,067,247	27,068,000
Ending balance at Sep. 30, 2020	$ 676,295	$ 446,155	$ 60,317	$ 507,602	$ 168,693		$ 859		$ 271