Unaudited Condensed Consolidated Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock [Member] Common Class A [Member] IPO [Member]	Common Stock [Member] Common Class A [Member]	Common Stock [Member] Common Class B [Member]	Additional Paid-in Capital [Member] Common Class A [Member]	Additional Paid-in Capital [Member] Common Class B [Member]	Additional Paid-in Capital [Member] IPO [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member] Common Class A [Member]	Retained Earnings [Member] Common Class B [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	IPO [Member]	Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of ASU | Accounting Standards Update 2014-09 [Member]										$ 1,459			$ 1,459
Temporary Equity, Beginning Balance at Dec. 31, 2017													3,281
Increase (Decrease) in Temporary Equity [Roll Forward]
Share-based compensation													208
Dividend of repurchased member units													(51)
Temporary Equity, Ending Balance at Mar. 31, 2018													3,438
Stockholders' Equity, Beginning Balance at Dec. 31, 2017		$ 64					$ 1			(43,459)	$ 2,289		(41,105)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income										1,159	223		1,382
Stockholders' Equity, Ending Balance at Mar. 31, 2018		64					1			(40,841)	2,512		(38,264)
Temporary Equity, Beginning Balance at Dec. 31, 2017													3,281
Stockholders' Equity, Beginning Balance at Dec. 31, 2017		64					1			(43,459)	2,289		(41,105)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income													2,417
Stockholders' Equity, Ending Balance at Jun. 30, 2018		328	$ 155				250,607			(40,460)	2,932		213,562
Temporary Equity, Beginning Balance at Mar. 31, 2018													3,438
Increase (Decrease) in Temporary Equity [Roll Forward]
Share-based compensation													183
Transfer from temporary equity to permanent equity													(3,455)
Dividend of repurchased member units													(166)
Stockholders' Equity, Beginning Balance at Mar. 31, 2018		64					1			(40,841)	2,512		(38,264)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation							238						238
Shares cancelled, value		(64)								64
Issuance of shares in reorganization, value		160	155	$ (11)	$ (6)			$ (149)	$ (149)
Transfer from temporary equity to permanent equity							3,455						3,455
Shares issued, value	$ 167					$ 246,931						$ 247,098
Vesting of restricted units		1					(1)
Net income										615	420		1,035
Stockholders' Equity, Ending Balance at Jun. 30, 2018		328	155				250,607			(40,460)	2,932		213,562
Stockholders' Equity, Beginning Balance at Dec. 31, 2018		329	155				251,742			(17,335)	3,496		238,387
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation							856						856
Vesting of restricted units			1				(39)						(38)
Net income										4,721	298		5,019
Stockholders' Equity, Ending Balance at Mar. 31, 2019		329	156				252,559			(12,614)	3,794		244,224
Stockholders' Equity, Beginning Balance at Dec. 31, 2018		329	155				251,742			(17,335)	3,496		238,387
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income													8,005
Stockholders' Equity, Ending Balance at Jun. 30, 2019		332	157				248,386			(9,942)	636		239,569
Stockholders' Equity, Beginning Balance at Mar. 31, 2019		329	156				252,559			(12,614)	3,794		244,224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation							1,024						1,024
Vesting of restricted units		3	1				(10)						(6)
Purchase of noncontrolling interest							(5,187)				(3,472)		(8,659)
Net income										2,672	314		2,986
Stockholders' Equity, Ending Balance at Jun. 30, 2019		$ 332	$ 157				$ 248,386			$ (9,942)	$ 636		$ 239,569