CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Previously Reported	Revision of Prior Period, Adjustment	Common Stock	Common Stock Previously Reported	Common Stock Revision of Prior Period, Adjustment	APIC	APIC Previously Reported	Note Receivable	Note Receivable Previously Reported	Accumulated Other Comprehensive Income	Accumulated Other Comprehensive Income Previously Reported	Accumulated Deficit	Accumulated Deficit Previously Reported
Beginning balance (in shares) at Dec. 31, 2020	68,776,614	67,728,286	1,048,328
Beginning balance at Dec. 31, 2020	$ 304,469	$ 304,469
Convertible Preferred Stock
Exercise of convertible preferred stock warrants (in shares)	3,974,655
Exercise of convertible preferred stock warrants	$ 132,718
Conversion of preferred stock to common (in shares)	(72,751,269)
Conversion of preferred stock to common	$ (437,187)
Ending balance (in shares) at Mar. 31, 2021	0
Ending balance at Mar. 31, 2021	$ 0
Beginning balance (in shares) at Dec. 31, 2020				8,992,039	8,854,978	137,061
Beginning balance at Dec. 31, 2020	(361,496)	$ (361,496)		$ 1	$ 1		$ 5,482	$ 5,482	$ (415)	$ (415)	$ 11	$ 11	$ (366,575)	$ (366,575)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	3,208						3,208
Exercises and vested portion of common stock options (in shares)				1,089,670
Exercises and vested portion of stock options	2,059						2,059
Conversion of promissory note	0						(415)		415
RSUs withheld for tax purposes	(422)						(422)
Unrealized net loss on marketable securities	(9)										(9)
Conversion of preferred stock to common (in shares)				72,751,269
Conversion of preferred stock to common	437,194			$ 7			437,187
Business Combination and PIPE financing (in shares)				43,894,156
Business Combination and PIPE financing	290,957			$ 4			290,953
Net loss	(103,627)												(103,627)
Ending balance (in shares) at Mar. 31, 2021				126,727,134
Ending balance at Mar. 31, 2021	$ 267,864			$ 12			738,052		0		2		(470,202)
Beginning balance (in shares) at Dec. 31, 2021	0
Beginning balance at Dec. 31, 2021	$ 0
Ending balance (in shares) at Mar. 31, 2022	0
Ending balance at Mar. 31, 2022	$ 0
Beginning balance (in shares) at Dec. 31, 2021				128,221,885
Beginning balance at Dec. 31, 2021	186,388			$ 13			769,525		0		(116)		(583,034)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
401K match with MILE stock (in shares)				110,364
401K match with MILE stock	553						553
Stock-based compensation (in shares)				1,851,013
Stock-based compensation	5,258						5,258
Exercises and vested portion of stock options	107						107
Unrealized net loss on marketable securities	(348)										(348)
Net loss	(34,319)												(34,319)
Ending balance (in shares) at Mar. 31, 2022				130,183,262
Ending balance at Mar. 31, 2022	$ 157,639			$ 13			$ 775,443		$ 0		$ (464)		$ (617,353)