Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (73,873)	$ (109,247)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,460	4,957
Stock-based compensation expense	2,566	9,115
Amortization of operating lease right-of-use assets	5,859	5,751
Contra-revenue associated with milestones	601	318
Amortization of debt discounts	1,192	843
Loss on impairment	2,270	0
Gain on disposal of long-lived assets	(1,825)	0
Changes in operating assets and liabilities:
Accounts receivable	1,869	11,185
Inventory	16,312	(14,001)
Prepaid expenses and other current assets	1,425	784
Other non-current assets	749	71
Accounts payable	(4,037)	8,712
Accrued expenses and other current liabilities	(16,656)	(11,802)
Operating lease liabilities	(7,076)	(3,160)
Other non-current liabilities	(123)	(1,659)
Net cash, cash equivalents, and restricted cash used in operating activities	(64,287)	(98,133)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(385)	(3,358)
Proceeds from sale of property and equipment	65	0
Proceeds from sales of marketable securities	806	0
Proceeds from commutation of reinsurance contracts	187	0
Proceeds from sale of discontinued operations	1,781	0
Capitalized website internal-use software costs	(3,273)	(5,072)
Cash paid for acquisition of Fair Dealer Services, LLC	0	(15,000)
Net cash, cash equivalents, and restricted cash used in investing activities	(819)	(23,430)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from flooring line of credit facility	48,666	270,083
Repayment of flooring line of credit facility	(59,061)	(259,505)
Proceeds from Senior Unsecured Notes, net of discounts	0	19,591
Payment of debt issuance costs	0	(175)
Principal payments on finance leases	(183)	0
Proceeds from disgorgement of stockholders' short-swing profits	75	0
Proceeds from stock option exercises, including from early exercised options	0	3
Payment of tax withheld for common stock issued under stock-based compensation plans	(70)	(2,453)
Repurchase of shares related to early exercised options	(1)	(40)
Net cash, cash equivalents, and restricted cash provided by (used in) financing activities	(10,574)	27,504
Net decrease in cash, cash equivalents and restricted cash	(75,680)	(94,059)
Cash, cash equivalents and restricted cash, beginning of period	107,846	194,341
Cash, cash equivalents and restricted cash, end of period	32,166	100,282
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest	5,537	5,221
Cash paid for income taxes	224	125
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES
Capital expenditures in accounts payable	6	163
Vesting of exercised options	25	59
Stock-based compensation capitalized to internal-use software	304	662
Issuance of shares as consideration in business acquisitions	0	2,481
Imputation of debt discounts reducing purchase consideration transferred in business acquisitions	0	2,103
Establishment of lease right of use assets and lease liabilities
Operating lease right of use assets	0	42,602
Operating lease liabilities	0	43,378
Other assets	0	1,716
Other liabilities	0	2,492
Termination of lease right of use assets and lease liabilities
Operating lease right of use assets	19,426	0
Operating lease liabilities	18,899	0
Finance lease right of use assets	6,857	0
Finance lease liabilities	$ 7,388	$ 0