Unaudited Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Class B Common Stock	Common Stock	Additional Paid-In Capital	Accumulate Deficit
Beginning balance at Dec. 31, 2019	$ (56,011)			$ 2,295	$ (148,354)
Beginning balance, share at Dec. 31, 2019			0
Net loss	(19,458)				(19,458)
Ending balance at Sep. 30, 2020	(74,521)		$ 1		(74,522)
Ending balance, share at Sep. 30, 2020			6,220,050
Beginning balance at Jun. 30, 2020	(63,837)			2,295	(156,180)
Beginning balance, share at Jun. 30, 2020			0
Net loss	(11,632)				(11,632)
Ending balance at Sep. 30, 2020	(74,521)		$ 1		(74,522)
Ending balance, share at Sep. 30, 2020			6,220,050
Beginning balance at Dec. 31, 2020	209,974	$ 0	$ 3	300,888	(90,917)
Beginning balance, share at Dec. 31, 2020		1,492,059	32,171,560
Stock-based compensation expense	21,307			21,307
Issuance of common stock, net of issuance costs	71,054		$ 1	71,053
Issuance of common stock, net of issuance costs, share			2,678,600
Issuance of common stock under equity incentive plans, share			327,241
Issuance of common stock for Employee Stock Purchase Plan	190			190
Issuance of common stock for Employee Stock Purchase Plan, share			5,280
Issuance of common stock upon exercise of options, net	140			140
Issuance of common stock upon exercise of options, net, share			7,747
Net loss	(72,012)				(72,012)
Ending balance at Sep. 30, 2021	230,653	$ 0	$ 4	393,578	(162,929)
Ending balance, share at Sep. 30, 2021		1,492,059	35,190,428
Beginning balance at Jun. 30, 2021	178,023	$ 0	$ 3	318,019	(139,999)
Beginning balance, share at Jun. 30, 2021		1,492,059	32,315,301
Stock-based compensation expense	4,366			4,366
Issuance of common stock, net of issuance costs	71,054		$ 1	71,053
Issuance of common stock, net of issuance costs, share			2,678,600
Issuance of common stock under equity incentive plans, share			188,780
Issuance of common stock upon exercise of options, net	140			140
Issuance of common stock upon exercise of options, net, share			7,747
Net loss	(22,930)				(22,930)
Ending balance at Sep. 30, 2021	$ 230,653	$ 0	$ 4	$ 393,578	$ (162,929)
Ending balance, share at Sep. 30, 2021		1,492,059	35,190,428