CONDENSED CONSOLIDATED STATEMENTS of CASH FLOWS (Unaudited) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended				6 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Cash flows from operating activities
Net income (loss)	$ 2,957	$ 2,979	$ (1,067)	$ (2,951)	$ 2,510	$ 1,912	$ (441)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization		791				1,551	1,192
Equity-based awards						818	77
Loss on asset disposals						90	50
Change in fair value of long-term warrant liability		0				(771)	7,600
Non-cash interest expense						3,307	1,406
Non-cash gain on settlement of contingent consideration						0	(1,655)
(Increase) decrease in assets:
Accounts receivable						(4,547)	(14,959)
Inventories						(56,039)	(86,863)
Prepaid expenses and other current assets						(4,495)	480
Deposits						(19)	14
Increase (decrease) in liabilities:
Accounts payable						2,273	6,412
Other payables and accrued expenses						251	1,549
Customer deposits						8,589	6,668
Net cash used in operating activities						(47,080)	(78,470)
Cash flows from investing activities
Purchases of property and equipment and construction in progress						(3,392)	(3,512)
Proceeds from disposal of property and equipment						1,574	50
Cash used in acquisitions						0	(2,111)
Net cash used in investing activities						(1,818)	(5,573)
Cash flows from financing activities
Net borrowings from floor plan						68,886	81,320
Proceeds from long-term debt						35,155	7,000
Payments on long-term debt						(4,155)	(465)
Payments of debt issuance costs						(791)	0
Payments of offering costs						(3,789)	0
Payment of acquisition contingent consideration						(1,457)	0
Distributions to redeemable preferred interest members						(90,503)	(823)
Proceeds from issuance of Class A common stock sold in initial public offering, net of underwriting discounts and commissions						59,234	0
Distributions to members						(4,206)	(1,725)
Net cash provided by financing activities						58,374	85,307
Net change in cash						9,476	1,264
Cash and restricted cash at beginning of period			$ 11,492		$ 15,757	11,492	15,757	$ 15,757
Cash and restricted cash at end of period	$ 20,968	$ 20,968		$ 17,021		20,968	17,021	$ 11,492
Supplemental cash flow disclosures
Cash paid for interest						6,187	5,113
Noncash items
Acquisition purchase price funded by long-term debt						0	8,500
Acquisition purchase price funded by seller notes payable						0	8,274
Purchase of property and equipment funded by long-term debt						625	993
Offering costs, accrued not yet paid						$ 600	$ 0