Condensed Consolidated and Combined Statement of Changes in Shareholders' and Members' Equity - USD ($) $ in Thousands	Total	Members' Contributed Capital	Additional Paid-in Capital	Accumulated Deficit	Treasury Stock	Class A Common Stock	Class A Common Stock Common Stock	Class B Common Stock	Class B Common Stock Common Stock
Beginning balance (in shares) at Dec. 31, 2018							0		0
Beginning balance at Dec. 31, 2018	$ 373,948		$ (3,057)	$ 168,277			$ 0		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to shareholders	534			534
Ending balance (in shares) at Mar. 31, 2019							0		0
Ending balance at Mar. 31, 2019	377,984		(3,057)	172,313			$ 0		$ 0
Beginning balance at Dec. 31, 2018		$ 208,728
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to predecessor	3,502			3,502
Ending balance at Mar. 31, 2019		208,728
Beginning balance (in shares) at Dec. 31, 2018							0		0
Beginning balance at Dec. 31, 2018	373,948		(3,057)	168,277			$ 0		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to shareholders	1,824
Ending balance (in shares) at Sep. 30, 2019							21,997,000		28,778,000
Ending balance at Sep. 30, 2019	59,478		63,203	(3,945)			$ 220		$ 0
Beginning balance at Dec. 31, 2018		208,728
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to predecessor	5,092
Ending balance at Sep. 30, 2019		0
Beginning balance (in shares) at Mar. 31, 2019							0		0
Beginning balance at Mar. 31, 2019	377,984		(3,057)	172,313			$ 0		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to shareholders	314			314
Ending balance (in shares) at Apr. 16, 2019							0		0
Ending balance at Apr. 16, 2019	379,888		(3,057)	174,217			$ 0		$ 0
Beginning balance at Mar. 31, 2019		208,728
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to predecessor	1,590			1,590
Ending balance at Apr. 16, 2019		208,728
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	7,505		7,505
Net income attributable to shareholders	(2,170)			(2,170)
Adjustment of temporary equity to carrying and redemption value	(97,344)		(97,344)
Ending balance (in shares) at Jun. 30, 2019							21,997,000		28,778,000
Ending balance at Jun. 30, 2019	58,456		57,719	517			$ 220		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of PE Units for Class A Common Stock and Class B Common Stock	0	(208,728)	380,205	(171,530)			$ 53
Conversion of PE Units for Class A Common Stock and Class B Common Stock (in shares)							5,322,000		28,778,000
Issuance of common stock in IPO, net of offering costs (in shares)							16,675,000
Issuance of common stock	274,913		274,746				$ 167
Deferred tax asset arising from the IPO	13,664		13,664
Reclassification of noncontrolling interests to temporary equity	(518,000)		(518,000)
Ending balance at Jun. 30, 2019		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	3,152		3,152
Dividends declared	(7,206)			(7,206)
Dividend equivalent rights declared	(402)			(402)
Net income attributable to shareholders	3,146			3,146
Adjustment of temporary equity to carrying and redemption value	3,797		3,797
Ending balance (in shares) at Sep. 30, 2019							21,997,000		28,778,000
Ending balance at Sep. 30, 2019	59,478		63,203	(3,945)			$ 220		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to predecessor	0
Issuance of common stock	(1,465)		(1,465)
Ending balance at Sep. 30, 2019		$ 0
Beginning balance (in shares) at Dec. 31, 2019					0	34,040,934	34,041,000	22,847,045	22,847,000
Beginning balance at Dec. 31, 2019	317,319		323,578	(6,599)	$ 0		$ 340		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares surrendered for tax withholdings on vested equity awards							(7,000)
Conversion of shares of Class B Common Stock to Class A Common Stock (in shares)							140,000		(140,000)
Conversion of shares of Class B Common Stock to Class A Common Stock	1,526		1,524				$ 2
Deferred tax asset arising from conversion of shares of Class B Common Stock to Class A Common Stock	204		204
Share-based compensation	3,402		3,402
Dividends declared	(12,945)			(12,945)
Dividend equivalent rights declared	(596)			(596)
Net income attributable to shareholders	4,706			4,706
Adjustment of temporary equity to carrying and redemption value	206,017		206,017
Ending balance (in shares) at Mar. 31, 2020					0		34,174,000		22,707,000
Ending balance at Mar. 31, 2020	519,633		534,725	(15,434)	$ 0		$ 342		$ 0
Beginning balance (in shares) at Dec. 31, 2019					0	34,040,934	34,041,000	22,847,045	22,847,000
Beginning balance at Dec. 31, 2019	317,319		323,578	(6,599)	$ 0		$ 340		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to shareholders	(8,809)
Ending balance (in shares) at Sep. 30, 2020					437,000	43,315,863	43,316,000	13,167,687	13,168,000
Ending balance at Sep. 30, 2020	582,534		633,634	(48,011)	$ (3,527)		$ 438		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to predecessor	0
Beginning balance (in shares) at Mar. 31, 2020					0		34,174,000		22,707,000
Beginning balance at Mar. 31, 2020	519,633		534,725	(15,434)	$ 0		$ 342		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares surrendered for tax withholdings on vested equity awards							(11,000)
Shares surrendered for tax withholdings on vested equity awards	(185)		(185)
Conversion of shares of Class B Common Stock to Class A Common Stock (in shares)							5,094,000		(5,094,000)
Conversion of shares of Class B Common Stock to Class A Common Stock	51,569		51,518				$ 51
Deferred tax asset arising from conversion of shares of Class B Common Stock to Class A Common Stock	(780)		(780)
Share-based compensation (in shares)							50,000
Share-based compensation	3,332		3,332
Restricted stock forfeited (in shares)							(9,000)
Dividends declared	(12,710)			(12,710)
Dividend equivalent rights declared	(562)			(562)
Net income attributable to shareholders	(4,050)			(4,050)
Adjustment of temporary equity to carrying and redemption value	(37,445)		(37,445)
Ending balance (in shares) at Jun. 30, 2020					0		39,298,000		17,613,000
Ending balance at Jun. 30, 2020	518,802		551,165	(32,756)	$ 0		$ 393		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of shares of Class B Common Stock to Class A Common Stock (in shares)							4,445,000		(4,445,000)
Conversion of shares of Class B Common Stock to Class A Common Stock	44,396		44,351				$ 45
Deferred tax asset arising from conversion of shares of Class B Common Stock to Class A Common Stock	(2,845)		(2,845)
Purchase of treasury stock (in shares)					437,000		(437,000)
Purchase of treasury stock	(3,527)				$ (3,527)
Share-based compensation (in shares)							10,000
Share-based compensation	3,518		3,518
Dividends declared	(5,567)			(5,567)
Dividend equivalent rights declared	(223)			(223)
Net income attributable to shareholders	(9,465)			(9,465)
Adjustment of temporary equity to carrying and redemption value	37,445		37,445
Ending balance (in shares) at Sep. 30, 2020					437,000	43,315,863	43,316,000	13,167,687	13,168,000
Ending balance at Sep. 30, 2020	582,534		$ 633,634	$ (48,011)	$ (3,527)		$ 438		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income attributable to predecessor	$ 0