Condensed Consolidated Statements of Capital - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed capital, beginning balance			$ 571,532
Capital attributable to parent, beginning balance			1,883,800
Total members' capital, beginning balance			611,694
Capital including portion attributable to noncontrolling interest, beginning balance	$ 1,839,592	$ 1,883,774	1,883,800	$ 1,848,517
Net (loss) income	36,422	(22,955)	(2,559)	7,150
Share-based compensation expense	2,848	3,400	8,696	10,158
Other comprehensive income—net of tax	25	37	73	107
Adjustment to liability recognized under tax receivable agreement—net of tax of $0			(615)	(3,124)
Reacquisition of share-based compensation awards for tax-withholding purposes			(5,521)	(4,099)
Tax distribution to noncontrolling interest			(4,568)
Contribution from noncontrolling interest and related sale of Class B common shares				5,547
Contributed capital, ending balance	575,412		575,412
Capital attributable to parent, ending balance	1,878,887		1,878,887
Total members' capital, ending balance	614,211		614,211
Capital including portion attributable to noncontrolling interest, ending balance	$ 1,878,887	$ 1,864,256	1,878,887	$ 1,864,256
Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital including portion attributable to noncontrolling interest, beginning balance			$ (419)
Class A Common Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares outstanding, beginning balance (in shares)			68,788,257
Common shares outstanding, ending balance (in shares)	69,051,284		69,051,284
Class B Common Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares outstanding, beginning balance (in shares)			79,233,544
Common shares outstanding, ending balance (in shares)	79,233,544		79,233,544
Common Stock | Class A Common Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares outstanding, beginning balance (in shares)	69,056,591	68,746,555	68,788,257	66,810,980
Issuance of share-based compensation awards, net of forfeitures (in shares)	(5,307)		364,624	1,894,168
Reacquisition of share-based compensation awards for tax-withholding purposes (in shares)			(436,675)	(296,392)
Settlement of restricted share units for Class A common shares (in shares)			335,078	337,799
Common shares outstanding, ending balance (in shares)	69,051,284	68,746,555	69,051,284	68,746,555
Common Stock | Class B Common Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common shares outstanding, beginning balance (in shares)	79,233,544	79,275,234	79,233,544	78,838,736
Contribution from noncontrolling interest and related sale of Class B common shares (in shares)				436,498
Common shares outstanding, ending balance (in shares)	79,233,544	79,275,234	79,233,544	79,275,234
Contributed Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Contributed capital, beginning balance	$ 572,587	$ 564,199	$ 571,532	$ 556,521
Share-based compensation expense	2,848	3,400	8,696	10,158
Adjustment of noncontrolling interest in the Operating Company	(23)		1,320	8,140
Adjustment to liability recognized under tax receivable agreement—net of tax of $0			(615)	(3,124)
Reacquisition of share-based compensation awards for tax-withholding purposes			(5,521)	(4,099)
Contribution from noncontrolling interest and related sale of Class B common shares				3
Contributed capital, ending balance	575,412	567,599	575,412	567,599
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital attributable to parent, beginning balance	24,475	47,107	42,844	33,811
Net (loss) income	16,964	(10,663)	(1,210)	2,633
Capital attributable to parent, ending balance	41,439	36,444	41,439	36,444
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital including portion attributable to noncontrolling interest, beginning balance			(195)
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital attributable to parent, beginning balance	(2,656)	(3,298)	(2,682)	(3,306)
Other comprehensive income—net of tax	16	23	46	67
Adjustment of noncontrolling interest in the Operating Company			(4)	(36)
Capital attributable to parent, ending balance	(2,640)	(3,275)	(2,640)	(3,275)
Total Members’ Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total members' capital, beginning balance	594,406	608,008	611,694	587,026
Net (loss) income	16,964	(10,663)	(1,210)	2,633
Share-based compensation expense	2,848	3,400	8,696	10,158
Other comprehensive income—net of tax	16	23	46	67
Adjustment of noncontrolling interest in the Operating Company	(23)		1,316	8,104
Adjustment to liability recognized under tax receivable agreement—net of tax of $0			(615)	(3,124)
Reacquisition of share-based compensation awards for tax-withholding purposes			(5,521)	(4,099)
Contribution from noncontrolling interest and related sale of Class B common shares				3
Total members' capital, ending balance	614,211	600,768	614,211	600,768
Total Members’ Capital | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital including portion attributable to noncontrolling interest, beginning balance			(195)
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital attributable to noncontrolling interests, beginning balance	1,245,186	1,275,766	1,272,106	1,261,491
Net (loss) income	19,458	(12,292)	(1,349)	4,517
Other comprehensive income—net of tax	9	14	27	40
Adjustment of noncontrolling interest in the Operating Company	23		(1,316)	(8,104)
Tax distribution to noncontrolling interest			(4,568)
Contribution from noncontrolling interest and related sale of Class B common shares				5,544
Capital attributable to noncontrolling interests, ending balance	$ 1,264,676	$ 1,263,488	1,264,676	$ 1,263,488
Noncontrolling Interests | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital including portion attributable to noncontrolling interest, beginning balance			$ (224)