Condensed Consolidated Statements of Capital - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	$ 1,822,494	$ 1,904,353	1,883,800	$ 1,848,517
Net (loss) income	14,238	(22,628)	(38,981)	30,105
Share-based compensation expense	2,836	3,442	5,848	6,758
Other comprehensive income—net of tax	24	35	48	70
Adjustment to liability recognized under tax receivable agreement—net of tax of $0		(1,428)	(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	572,587		572,587
Capital attributable to parent, ending balance	1,839,592		1,839,592
Total members' capital, ending balance	594,406		594,406
Capital including portion attributable to noncontrolling interest, ending balance	$ 1,839,592	$ 1,883,774	1,839,592	$ 1,883,774
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)	69,056,591		69,056,591
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)	69,061,898	68,746,555	68,788,257	66,810,980
Issuance of share-based compensation awards, net of forfeitures (in shares)	(5,307)		369,931	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)	69,056,591	68,746,555	69,056,591	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	$ 569,772	$ 562,185	$ 571,532	$ 556,521
Share-based compensation expense	2,836	3,442	5,848	6,758
Adjustment of noncontrolling interest in the Operating Company	(21)		1,343	8,140
Adjustment to liability recognized under tax receivable agreement—net of tax of $0		(1,428)	(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	572,587	564,199	572,587	564,199
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital attributable to parent, beginning balance	17,843	57,619	42,844	33,811
Net (loss) income	6,632	(10,512)	(18,174)	13,296
Capital attributable to parent, ending balance	24,475	47,107	24,475	47,107
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	(2,671)	(3,320)	(2,682)	(3,306)
Other comprehensive income—net of tax	15	22	30	44
Adjustment of noncontrolling interest in the Operating Company			(4)	(36)
Capital attributable to parent, ending balance	(2,656)	(3,298)	(2,656)	(3,298)
Total Members’ Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total members' capital, beginning balance	584,944	616,484	611,694	587,026
Net (loss) income	6,632	(10,512)	(18,174)	13,296
Share-based compensation expense	2,836	3,442	5,848	6,758
Other comprehensive income—net of tax	15	22	30	44
Adjustment of noncontrolling interest in the Operating Company	(21)		1,339	8,104
Adjustment to liability recognized under tax receivable agreement—net of tax of $0		(1,428)	(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	594,406	608,008	594,406	608,008
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	1,237,550	1,287,869	1,272,106	1,261,491
Net (loss) income	7,606	(12,116)	(20,807)	16,809
Other comprehensive income—net of tax	9	13	18	26
Adjustment of noncontrolling interest in the Operating Company	21		(1,339)	(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	$ 1,245,186	$ 1,275,766	1,245,186	$ 1,275,766
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)