UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital Series A Convertible Preferred Stock	Additional Paid-in Capital Series B Convertible Preferred Stock	Additional Paid-in Capital Series C Convertible Preferred Stock	Additional Paid-in Capital	Accumulated Deficit Series A Convertible Preferred Stock	Accumulated Deficit Series B Convertible Preferred Stock	Accumulated Deficit Series C Convertible Preferred Stock	Accumulated Deficit	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Total
Beginning balance at Dec. 31, 2019									$ (422,862)				$ (422,862)
Convertible Preferred Stock, beginning balance, Shares at Dec. 31, 2019													318,510,205
Convertible Preferred Stock, beginning balance at Dec. 31, 2019													$ 411,275
Beginning balance, shares at Dec. 31, 2019	7,787,470
Net income (loss)									(36,736)				(36,736)
Preferred stock dividend		$ (1,048)	$ 1			$ (21,732)	$ (778)	$ (3,347)		$ (22,780)	$ (777)	$ (3,347)
Preferred stock accretion		(3,572)	(37)	$ (563)		(1,990)	(16)	(359)		(5,562)	(53)	(922)
Temporary equity, Preferred stock dividend										22,780	777	3,347
Temporary equity, Preferred stock accretion										$ 5,562	$ 53	$ 921
Issuance of common stock					$ 135,435								135,435
Issuance of common stock (in shares)	6,151,162
Issuance of Series A, B, C convertible stock to common stock	$ 1				444,715								444,716
Issuance of Series A, B, C convertible stock to common stock, Shares	42,926,630
Temporary equity, Issuance of Series A, B, C convertible stock to common stock													$ (444,715)
Temporary equity, Issuance of Series A, B, C convertible stock to common stock, Shares													(318,510,205)
Reclassification of warrant liability to equity					5,468								$ 5,468
Exercise of stock options					283								283
Exercise of stock options, Shares	36,003
Stock-based compensation					1,870								1,870
Repurchase and cancellation of common units									(167)				(167)
Repurchase and cancellation of common shares, Shares	(12,175)
Repurchase and cancellation of common units withheld for taxes					(17)								(17)
Repurchase and cancellation of common units withheld for taxes, Shares	(465)
Ending balance at Sep. 30, 2020	$ 1				582,535				(487,987)				94,549
Convertible Preferred Stock, Ending balance, Shares at Sep. 30, 2020										285,000,000	8,000,000	25,510,205
Ending balance, shares at Sep. 30, 2020	56,888,625
Beginning balance at Jun. 30, 2020									(483,362)				$ (483,362)
Convertible Preferred Stock, beginning balance, Shares at Jun. 30, 2020													318,510,205
Convertible Preferred Stock, beginning balance at Jun. 30, 2020													$ 434,009
Beginning balance, shares at Jun. 30, 2020	7,805,848
Net income (loss)									1,909				1,909
Preferred stock dividend						(5,091)	(174)	(748)		$ (5,091)	$ (174)	$ (748)
Preferred stock accretion		$ (3,572)	$ (37)	$ (563)		$ (438)	$ (4)	$ (79)		(4,010)	(41)	(642)
Temporary equity, Preferred stock dividend										5,091	174	748
Temporary equity, Preferred stock accretion										$ 4,010	$ 41	$ 642
Issuance of common stock					135,435								135,435
Issuance of common stock (in shares)	6,151,162
Issuance of Series A, B, C convertible stock to common stock	$ 1				444,715								444,716
Issuance of Series A, B, C convertible stock to common stock, Shares	42,926,630
Temporary equity, Issuance of Series A, B, C convertible stock to common stock													$ (444,715)
Temporary equity, Issuance of Series A, B, C convertible stock to common stock, Shares													(318,510,205)
Reclassification of warrant liability to equity					5,468								$ 5,468
Exercise of stock options					33								33
Exercise of stock options, Shares	5,450
Stock-based compensation					1,073								1,073
Repurchase and cancellation of common units withheld for taxes					(17)								(17)
Repurchase and cancellation of common units withheld for taxes, Shares	(465)
Ending balance at Sep. 30, 2020	$ 1				582,535				(487,987)				94,549
Convertible Preferred Stock, Ending balance, Shares at Sep. 30, 2020										285,000,000	8,000,000	25,510,205
Ending balance, shares at Sep. 30, 2020	56,888,625
Beginning balance at Dec. 31, 2020	$ 1				585,374				(488,195)				97,180
Beginning balance, shares at Dec. 31, 2020	56,890,569
Net income (loss)									11,883				11,883
Issuance of common stock					29,700								29,700
Issuance of common stock (in shares)	1,270,462
Exercise of stock options					1,794								$ 1,794
Exercise of stock options, Shares	253,515												268,569
Stock-based compensation					11,461								$ 11,461
Ending balance at Sep. 30, 2021	$ 1				628,329				(476,312)				152,018
Ending balance, shares at Sep. 30, 2021	58,414,546
Beginning balance at Jun. 30, 2021	$ 1				593,242				(466,692)				126,551
Beginning balance, shares at Jun. 30, 2021	57,000,139
Net income (loss)									(9,620)				(9,620)
Issuance of common stock					29,700								29,700
Issuance of common stock (in shares)	1,270,462
Exercise of stock options					1,134								1,134
Exercise of stock options, Shares	143,945
Stock-based compensation					4,253								4,253
Ending balance at Sep. 30, 2021	$ 1				$ 628,329				$ (476,312)				$ 152,018
Ending balance, shares at Sep. 30, 2021	58,414,546