CONDENSED 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, 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 and Reorganization			(13,648)					(13,648)
Effect of IPO and Reorganization	$ 265		$ 48,651	$ 71,195			$ 130,861	250,972
Effect of IPO and Reorganization (shares)	26,450	48,440
Member distribution after IPO							(41)	(41)
Additional paid-in capital related to tax receivable agreement				11,116				11,116
Other comprehensive income						239		239
Stock-based compensation				834				834
Net income after IPO and Reorganization					$ 3,753		9,007	12,760
Balance at the end of the period at Mar. 31, 2018	$ 265			83,145	3,753	321	139,827	227,311
Balance at the end of the period (shares) at Mar. 31, 2018	26,450	48,440
Balance at the beginning of the period at Dec. 31, 2018	$ 377			126,418	51,683	(820)	184,670	362,328
Balance at the beginning of the period (shares) at Dec. 31, 2018	37,654	37,236
Statement of Stockholders'/Members' Equity
Correction to equity reclassification related to prior equity offering				14,035		488	(14,523)
Member distribution after IPO							(235)	(235)
Effect of Follow-on Offering and CW redemptions	$ 85			43,899		(50)	(43,934)
Effect of Follow-on Offering and CW redemptions (in shares)	8,518	(8,518)
Adjustment to deferred tax asset from CW Unit redemptions				(8,232)				(8,232)
Additional paid-in capital related to tax receivable agreement				13,580				13,580
Other comprehensive income						123	147	270
Equity award vestings	$ 2			(1,474)				(1,472)
Equity award vestings (in shares)	219
Stock-based compensation				1,676				1,676
Net income after IPO and Reorganization					26,807		21,639	48,446
Balance at the end of the period at Mar. 31, 2019	$ 464			$ 189,902	$ 78,490	$ (259)	$ 147,764	$ 416,361
Balance at the end of the period (shares) at Mar. 31, 2019	46,391	28,718