Consolidated Statements of Stockholders' /Members' Equity (Deficit) and Mezzanine Equity (Unaudited) - USD ($) $ in Thousands	Total	APIC	Accumulated Deficit	Members’ Deficit	Notes Receivable from Stockholders/ Members	Noncontrolling Interest	Redeemable Noncontrolling Interest	Redeemable Members’ Capital	Common Class A Common Stock	Common Class B Common Stock
Balance at beginning of period, stockholders'/members' equity (deficit) at Dec. 31, 2018	$ (62,759)			$ (63,606)	$ (90)	$ 937
Balance at beginning of period, mezzanine equity at Dec. 31, 2018							$ 46,208	$ 39,354
Stockholders' Equity [Roll Forward]
Net income (loss)	231			119		112	3,761	485
Contributions							35
Contributions through issuance of member notes receivable	(263)				(310)	47	263
Repayment of member notes receivable	160				160
Issuance and vesting of Management Incentive Units	663			663
Issuance of common units	998			612		386
Issuance of common units	5,509							5,509
Repurchase redemption value adjustments								(1,323)
Equity issued in business combinations	1,000					1,000	37,637
Redemptions and repurchases of common stock/ common units								(11,177)
Change in the redemption value of redeemable interests	(140,708)			(140,708)			167	140,541
Distributions	(3,217)			(3,122)		(95)	(5,463)	(1,151)
Balance at end of period, stockholders'/members' equity (deficit) at Sep. 30, 2019	(203,895)			(206,042)	(240)	2,387
Balance at end of period, mezzanine equity at Sep. 30, 2019							82,608	172,238
Balance at beginning of period, stockholders'/members' equity (deficit) at Jun. 30, 2019	(126,701)			(128,869)	(256)	2,424
Balance at beginning of period, mezzanine equity at Jun. 30, 2019							65,906	110,596
Stockholders' Equity [Roll Forward]
Net income (loss)	(2,598)			(2,578)		(20)	1,440	(1,148)
Contributions							1
Repayment of member notes receivable	16				16
Issuance and vesting of Management Incentive Units	303			303
Issuance of common units	0
Equity issued in business combinations							6,674
Change in the redemption value of redeemable interests	(74,166)			(74,166)			11,125	63,041
Distributions	(749)			(732)		(17)	(2,538)	(251)
Balance at end of period, stockholders'/members' equity (deficit) at Sep. 30, 2019	(203,895)			$ (206,042)	(240)	2,387
Balance at end of period, mezzanine equity at Sep. 30, 2019							82,608	$ 172,238
Balance at beginning of period (in shares) at Dec. 31, 2019									19,362,984	43,257,738
Balance at beginning of period, stockholders'/members' equity (deficit) at Dec. 31, 2019	237,251	$ 82,425	$ (8,650)		(688)	163,966			$ 194	$ 4
Balance at beginning of period, mezzanine equity at Dec. 31, 2019							23
Stockholders' Equity [Roll Forward]
Net income (loss)	(10,826)		(5,388)			(5,438)	59
Issuance of Class A common stock in offering, net of underwriting discounts and offering costs (in shares)									13,225,000	(2,475,000)
Issuance of Class A common stock in offering, net of underwriting discounts and offering costs	135,231	144,497				(9,398)			$ 132
Contributions							19
Issuance of common units	0
Equity issued in business combinations (in shares)									513,025	4,805,572
Equity issued in business combinations	52,575	8,117				44,453			$ 5
Share-based compensation, net of forfeitures (in shares)									580,045
Share-based compensation, net of forfeitures	3,486	2,600				880			$ 6
Redemptions and repurchases of common stock (in shares)									251,814	(340,599)
Redemptions and repurchases of common stock/ common units	(1,292)	5				(1,299)			$ 2
Repayment of stockholder notes receivable	169				169
Change in the redemption value of redeemable interests	0
Balance at end of period (in shares) at Sep. 30, 2020									33,932,868	45,247,711
Balance at end of period, stockholders'/members' equity (deficit) at Sep. 30, 2020	416,594	237,644	(14,038)		(519)	193,164			$ 339	$ 4
Balance at end of period, mezzanine equity at Sep. 30, 2020							101
Balance at beginning of period (in shares) at Jun. 30, 2020									33,302,477	45,458,763
Balance at beginning of period, stockholders'/members' equity (deficit) at Jun. 30, 2020	422,563	235,520	(10,770)		(573)	198,049			$ 333	$ 4
Balance at beginning of period, mezzanine equity at Jun. 30, 2020							71
Stockholders' Equity [Roll Forward]
Net income (loss)	(7,637)		(3,268)			(4,369)	22
Offering costs	(28)	(28)
Contributions							8
Equity issued in business combinations (in shares)									25,491	0
Equity issued in business combinations	445	445				0			$ 0
Share-based compensation, net of forfeitures (in shares)									393,848
Share-based compensation, net of forfeitures	1,197	908				285			$ 4
Redemptions and repurchases of common stock (in shares)									211,052	(211,052)
Redemptions and repurchases of common stock/ common units	0	799				(801)			$ 2
Repayment of stockholder notes receivable	54				54
Balance at end of period (in shares) at Sep. 30, 2020									33,932,868	45,247,711
Balance at end of period, stockholders'/members' equity (deficit) at Sep. 30, 2020	$ 416,594	$ 237,644	$ (14,038)		$ (519)	$ 193,164			$ 339	$ 4
Balance at end of period, mezzanine equity at Sep. 30, 2020							$ 101