Condensed Consolidated Statements Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Total	Previously Reported	Revision of Prior Period, Adjustment	Common Stock	Common Stock Previously Reported	Common Stock Revision of Prior Period, Adjustment	Additional Paid-in Capital	Additional Paid-in Capital Previously Reported	Additional Paid-in Capital Revision of Prior Period, Adjustment	Accumulated Deficit	Accumulated Deficit Previously Reported	Accumulated Deficit Revision of Prior Period, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Previously Reported	Accumulated Other Comprehensive Income (Loss) Revision of Prior Period, Adjustment
Beginning balance (in shares) at Dec. 31, 2019	0	2,034,751	(2,034,751)
Beginning balance at Dec. 31, 2019	$ 0	$ 17,560	$ (17,560)
Ending balance (in shares) at Mar. 31, 2020	0
Ending balance at Mar. 31, 2020	$ 0
Beginning balance (in shares) at Dec. 31, 2019				58,621,042	37,881,435	20,739,607
Beginning balance at Dec. 31, 2019	(4,861)	$ (22,421)	$ 17,560	$ 6	$ 4	$ 2	$ 22,618	$ 5,060	$ 17,558		$ (27,485)		$ (27,485)		$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(1,507)									$ (1,507)
Accrued dividends on redeemable convertible preferred stock	(456)						(456)
Redeemable convertible preferred stock issuance	4												4
Stock-based compensation	34						34
Ending balance (in shares) at Mar. 31, 2020				58,621,042
Ending balance at Mar. 31, 2020	$ (6,786)			$ 6			22,196			(28,992)			4
Beginning balance (in shares) at Dec. 31, 2019	0	2,034,751	(2,034,751)
Beginning balance at Dec. 31, 2019	$ 0	$ 17,560	$ (17,560)
Ending balance (in shares) at Sep. 30, 2020	0
Ending balance at Sep. 30, 2020	$ 0
Beginning balance (in shares) at Dec. 31, 2019				58,621,042	37,881,435	20,739,607
Beginning balance at Dec. 31, 2019	(4,861)	$ (22,421)	$ 17,560	$ 6	$ 4	$ 2	22,618	5,060	17,558		(27,485)		(27,485)		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(2,212)
Other comprehensive income, net of tax	16
Ending balance (in shares) at Sep. 30, 2020				58,621,042
Ending balance at Sep. 30, 2020	$ (8,419)			$ 6			21,256			(29,697)			16
Beginning balance (in shares) at Mar. 31, 2020	0
Beginning balance at Mar. 31, 2020	$ 0
Ending balance (in shares) at Jun. 30, 2020	0
Ending balance at Jun. 30, 2020	$ 0
Beginning balance (in shares) at Mar. 31, 2020				58,621,042
Beginning balance at Mar. 31, 2020	(6,786)			$ 6			22,196			(28,992)			4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(213)									(213)
Other comprehensive income, net of tax	7												7
Accrued dividends on redeemable convertible preferred stock	(466)						(466)
Stock-based compensation	3						3
Ending balance (in shares) at Jun. 30, 2020				58,621,042
Ending balance at Jun. 30, 2020	$ (7,455)			$ 6			21,733			(29,205)			11
Ending balance (in shares) at Sep. 30, 2020	0
Ending balance at Sep. 30, 2020	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(492)									(492)
Other comprehensive income, net of tax	5												5
Accrued dividends on redeemable convertible preferred stock	(477)						(477)
Ending balance (in shares) at Sep. 30, 2020				58,621,042
Ending balance at Sep. 30, 2020	$ (8,419)			$ 6			21,256			(29,697)			16
Beginning balance (in shares) at Dec. 31, 2020	0	2,034,751	(2,034,751)
Beginning balance at Dec. 31, 2020	$ 0	$ 17,560	$ (17,560)
Ending balance (in shares) at Mar. 31, 2021	0
Ending balance at Mar. 31, 2021	$ 0
Beginning balance (in shares) at Dec. 31, 2020	58,621,042			58,621,042	37,881,435	20,739,607
Beginning balance at Dec. 31, 2020	$ (13,237)	$ (30,797)	$ 17,560	$ 6	$ 4	$ 2	20,779	3,221	17,558	(34,037)	(34,037)	$ 0	15	$ 15	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(15,022)									(15,022)
Other comprehensive income, net of tax	(131)												(131)
Accrued dividends on redeemable convertible preferred stock	(19)						(19)
PIPE issuance (in shares)				12,500,000
PIPE issuance	125,000			$ 1			124,999
Merger financing (in shares)				38,194,390
Merger financing	309,999			$ 4			309,995
Consideration to existing shareholders of Former CarLotz, net of accrued dividends	(62,693)						(62,693)
Transaction costs and advisory fees	(47,579)						(47,579)
Settlement of redeemable convertible preferred stock tranche obligation	2,832						2,832
Cashless exercise of options (in shares)				54,717
Cash consideration paid to Former Carlotz optionholders	(2,465)						(2,465)
Stock-based compensation	41,963						41,963
Earnout liability	(74,284)						(74,284)
Merger warrants liability	(39,025)						(39,025)
KAR/AFC warrant exercise (in shares)				3,546,984
KAR/AFC note payable conversion	3,625						3,625
KAR/AFC warrant exercise (in shares)				752,927
KAR/AFC warrant exercise	144						144
Ending balance (in shares) at Mar. 31, 2021				113,670,060
Ending balance at Mar. 31, 2021	$ 229,108			$ 11			278,272			(49,059)			(116)
Beginning balance (in shares) at Dec. 31, 2020	0	2,034,751	(2,034,751)
Beginning balance at Dec. 31, 2020	$ 0	$ 17,560	$ (17,560)
Ending balance (in shares) at Sep. 30, 2021	0
Ending balance at Sep. 30, 2021	$ 0
Beginning balance (in shares) at Dec. 31, 2020	58,621,042			58,621,042	37,881,435	20,739,607
Beginning balance at Dec. 31, 2020	$ (13,237)	$ (30,797)	$ 17,560	$ 6	$ 4	$ 2	20,779	$ 3,221	$ 17,558	(34,037)	$ (34,037)	$ 0	15	$ 15	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(25,703)
Other comprehensive income, net of tax	$ (115)
Cashless exercise of options (in shares)	56,059
Ending balance (in shares) at Sep. 30, 2021	58,621,042			113,707,013
Ending balance at Sep. 30, 2021	$ 225,594			$ 11			285,423			(59,740)			(100)
Beginning balance (in shares) at Mar. 31, 2021	0
Beginning balance at Mar. 31, 2021	$ 0
Ending balance (in shares) at Jun. 30, 2021	0
Ending balance at Jun. 30, 2021	$ 0
Beginning balance (in shares) at Mar. 31, 2021				113,670,060
Beginning balance at Mar. 31, 2021	229,108			$ 11			278,272			(49,059)			(116)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(7,205)									(7,205)
Other comprehensive income, net of tax	56												56
Stock-based compensation	3,704						3,704
Ending balance (in shares) at Jun. 30, 2021				113,670,060
Ending balance at Jun. 30, 2021	$ 225,663			$ 11			281,976			(56,264)			(60)
Ending balance (in shares) at Sep. 30, 2021	0
Ending balance at Sep. 30, 2021	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(3,476)									(3,476)
Other comprehensive income, net of tax	(40)												(40)
Stock-based compensation	$ 3,447						3,447
Issuance of Class A common stock to settle vested restricted stock units (in shares)				36,953
Ending balance (in shares) at Sep. 30, 2021	58,621,042			113,707,013
Ending balance at Sep. 30, 2021	$ 225,594			$ 11			$ 285,423			$ (59,740)			$ (100)