CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Class A Common Stock Common stock	Class B Common Stock Common stock	Members' Equity (Deficit)	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest	Total
Balance at the beginning of the period at Dec. 31, 2016			$ (102,846)			$ (475)		$ (103,321)
Statement of Stockholders'/Members' Equity
Other comprehensive income (loss)						557		557
Net income			66,547					66,547
Balance at the end of the period at Dec. 31, 2017			(36,299)			82		(36,217)
Statement of Stockholders'/Members' Equity
Member distributions prior to IPO			(26,000)					(26,000)
Net income prior to IPO			13,648					13,648
Effect of IPO	$ 265		$ 48,651	$ 71,196			$ 130,861	250,973
Effect of IPO (shares)	26,450	48,440
Member distribution after IPO							(5,848)	(5,848)
Effect of Follow-on Offering and CW Unit redemptions	$ 112			24,472			(25,293)	(709)
Effect of Follow-on Offering and CW Unit redemptions (in shares)	11,204	(11,204)
Additional paid-in capital related to tax receivable agreement				26,046				26,046
Other comprehensive income (loss)						(902)		(902)
Stock-based compensation				4,704				4,704
Net income					$ 51,683		84,950	136,633
Balance at the end of the period at Dec. 31, 2018	$ 377			126,418	51,683	(820)	184,670	362,328
Balance at the end of the period (shares) at Dec. 31, 2018	37,654	37,236
Statement of Stockholders'/Members' Equity
Adjustments to prior periods				10,424		409	(11,339)	(506)
Member distribution after IPO							(8,392)	(8,392)
Effect of CW Unit redemptions	$ 93			48,635		(59)	(48,669)
Effect of CW Unit redemptions (in shares)	9,278	(9,278)
Adjustment to deferred tax asset from CW Unit redemptions				(9,751)				(9,751)
Additional paid-in capital related to tax receivable agreement				15,250				15,250
Equity award vestings	$ 2			(791)			(760)	(1,549)
Equity award vestings (in shares)	227
Other comprehensive income (loss)						18	4	22
Stock-based compensation				4,271			2,724	6,995
Cash dividends declared					(4,305)			(4,305)
Net income					85,612		70,691	156,303
Balance at the end of the period at Dec. 31, 2019	$ 472			$ 194,456	$ 132,990	$ (452)	$ 188,929	$ 516,395
Balance at the end of the period (shares) at Dec. 31, 2019	47,159	27,958