CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands		Total		Common Stock		Preferred Stock	[1]	Common Stock	Common Stock Common Stock	Common Stock Preferred Stock	Additional paid-in capital	Accumulated deficit		Accumulated deficit Common Stock	Accumulated deficit Preferred Stock
Shares, beginning balance (in shares) at Dec. 31, 2019	[1]							286,074,923
Beginning balance at Dec. 31, 2019	[1]	$ 18,665						$ 29			$ 108,892	$ (90,256)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	[1]							829,348
Issuance of common stock upon exercise of stock options	[1]	241									241
Stock-based compensation	[1]	357									357
Net loss	[1]	(15,522)										(15,522)
Shares, ending balance (in shares) at Mar. 31, 2020	[1]							286,904,271
Ending balance at Mar. 31, 2020	[1]	3,741						$ 29			109,490	(105,778)
Shares, beginning balance (in shares) at Dec. 31, 2019	[1]							286,074,923
Beginning balance at Dec. 31, 2019	[1]	18,665						$ 29			108,892	(90,256)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	[2]	(78,530)
Shares, ending balance (in shares) at Sep. 30, 2020	[1]							319,814,293
Ending balance at Sep. 30, 2020	[1]	46,232						$ 32			217,435	(171,235)
Shares, beginning balance (in shares) at Mar. 31, 2020	[1]							286,904,271
Beginning balance at Mar. 31, 2020	[1]	3,741						$ 29			109,490	(105,778)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	[1]							1,029,833
Issuance of common stock upon exercise of stock options	[1]	130									130
Stock-based compensation	[1]	5,546									5,546
Net loss	[1]	(20,157)										(20,157)
Shares issued (in shares)	[1]							15,091,869
Shares issued	[1]	64,879						$ 2			64,877
Issuance of common stock upon exercise of stock options with promissory note (in shares)	[1]							12,700,357
Issuance of common stock upon exercise of stock options with promissory note	[1]	1						$ 1
Repurchase of stock (in shares)	[1]								(270,599)
Repurchase of stock	[1]			$ (543)										$ (543)
Shares, ending balance (in shares) at Jun. 30, 2020	[1]							315,455,731
Ending balance at Jun. 30, 2020	[1]	53,597						$ 32			180,043	(126,478)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	[1]							2,102,672
Issuance of common stock upon exercise of stock options	[1]	302									302
Stock-based compensation	[1]	3,662									3,662
Net loss	[1]	(42,851)										(42,851)
Shares issued (in shares)	[1]							2,739,398
Shares issued	[1]	33,428						$ 0			33,428
Issuance of common stock upon exercise of stock options with promissory note (in shares)	[1]							0
Issuance of common stock upon exercise of stock options with promissory note	[1]	0						$ 0
Repurchase of stock (in shares)	[1]								(186,775)	(296,733)
Repurchase of stock				$ (695)	[1]	$ (1,211)								$ (695)	$ (1,211)
Shares, ending balance (in shares) at Sep. 30, 2020	[1]							319,814,293
Ending balance at Sep. 30, 2020	[1]	46,232						$ 32			217,435	(171,235)
Shares, beginning balance (in shares) at Dec. 31, 2020	[1]							369,797,524
Beginning balance at Dec. 31, 2020	[1]	56,787						$ 37			295,065	(238,315)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	[1]							268,426
Issuance of common stock upon exercise of stock options	[1]	12									12
Stock-based compensation	[1]	10,945									10,945
Net loss	[1]	(53,592)										(53,592)
Shares issued (in shares)	[1]							17,000,000
Shares issued	[1]	402,240						$ 2			402,238
Issuance of common stock upon exercise of warrants and other, net (in shares)	[1]							8,741,863
Issuance of common stock upon exercise of warrants and other, net	[1]	172,519									172,519
Shares, ending balance (in shares) at Mar. 31, 2021	[1]							395,807,813
Ending balance at Mar. 31, 2021	[1]	588,911						$ 39			880,779	(291,907)
Shares, beginning balance (in shares) at Dec. 31, 2020	[1]							369,797,524
Beginning balance at Dec. 31, 2020	[1]	$ 56,787						$ 37			295,065	(238,315)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		4,896,629
Net loss	[2]	$ (82,406)
Shares, ending balance (in shares) at Sep. 30, 2021	[1]							407,702,608
Ending balance at Sep. 30, 2021	[1]	704,336						$ 40			1,025,017	(320,721)
Shares, beginning balance (in shares) at Mar. 31, 2021	[1]							395,807,813
Beginning balance at Mar. 31, 2021	[1]	588,911						$ 39			880,779	(291,907)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	[1]							235,054
Issuance of common stock upon exercise of stock options	[1]	97									97
Stock-based compensation	[1]	15,774									15,774
Net loss	[1]	(79,595)										(79,595)
Issuance of common stock upon exercise of warrants and other, net (in shares)	[1]							628,576
Issuance of common stock upon exercise of warrants and other, net	[1]	9,625									9,625
Shares, ending balance (in shares) at Jun. 30, 2021	[1]							396,671,443
Ending balance at Jun. 30, 2021	[1]	534,812						$ 39			906,275	(371,502)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	[1]							4,393,149
Issuance of common stock upon exercise of stock options	[1]	3,056									3,056
Stock-based compensation	[1]	15,812									15,812
Net loss		50,781	[2]									50,781	[1]
Issuance of common stock upon exercise of warrants and other, net (in shares)	[1]							2,236,383
Issuance of common stock upon exercise of warrants and other, net	[1]	32,968						$ 1			32,967
Issuance of common stock for business combination (in shares)	[1]							4,401,633
Issuance of common stock for business combination	[1]	66,907									66,907
Shares, ending balance (in shares) at Sep. 30, 2021	[1]							407,702,608
Ending balance at Sep. 30, 2021	[1]	$ 704,336						$ 40			$ 1,025,017	$ (320,721)

[1] Retroactively restated for the reverse recapitalization as described in Notes 1 and 3.

[2] Retroactively restated for the reverse recapitalization as described in Notes 1 and 3.