CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Series C Preferred Stock	Series D Preferred Stock	Series A-1 and Series B Warrants	IPO	IPO Convertible Preferred Stock	Transition Adjustment	Common Stock	Common Stock IPO	Additional Paid-in Capital	Additional Paid-in Capital Series A-1 and Series B Warrants	Additional Paid-in Capital IPO	Accumulated Other Comprehensive Income	Accumulated Deficit	Accumulated Deficit Transition Adjustment
Beginning balance at Dec. 31, 2018	$ (76,718)								$ 2		$ (11,026)				$ (65,694)
Beginning balance, Shares at Dec. 31, 2018		18,200,011
Beginning balance at Dec. 31, 2018		$ 72,460
Beginning balance, Shares at Dec. 31, 2018									12,275,579
Net loss	(13,334)														(13,334)
Issuance of common stock under employee stock compensation plans	18										18
Issuance of common stock under employee stock compensation plans, Shares									16,594
Issuance of preferred stock for cash net of issuance costs, Shares			8,457,758
Issuance of preferred stock for cash net of issuance costs			$ 85,954
Stock-based compensation expense	454										454
Ending balance at Mar. 31, 2019	(89,580)								$ 2		(10,554)				(79,027)
Ending balance, Shares at Mar. 31, 2019		26,657,769
Ending balance at Mar. 31, 2019		$ 158,414
Ending balance, Shares at Mar. 31, 2019									12,292,173
Beginning balance at Dec. 31, 2018	(76,718)								$ 2		(11,026)				(65,694)
Beginning balance, Shares at Dec. 31, 2018		18,200,011
Beginning balance at Dec. 31, 2018		$ 72,460
Beginning balance, Shares at Dec. 31, 2018									12,275,579
Net loss	(62,914)
Ending balance at Sep. 30, 2019	(127,248)								$ 2		1,362			$ (3)	(128,608)
Ending balance, Shares at Sep. 30, 2019		32,934,785
Ending balance at Sep. 30, 2019		$ 222,173
Ending balance, Shares at Sep. 30, 2019									13,193,122
Beginning balance at Dec. 31, 2018	(76,718)								$ 2		(11,026)				(65,694)
Beginning balance, Shares at Dec. 31, 2018		18,200,011
Beginning balance at Dec. 31, 2018		$ 72,460
Beginning balance, Shares at Dec. 31, 2018									12,275,579
Net loss	(86,500)
Ending balance at Dec. 31, 2019	$ (149,511)							$ 111	$ 2		2,689			19	(152,221)	$ 111
Ending balance, Shares at Dec. 31, 2019	32,934,785	32,934,785	14,734,774
Ending balance at Dec. 31, 2019	$ 222,173	$ 222,173	$ 149,713
Ending balance, Shares at Dec. 31, 2019									13,196,419
Beginning balance at Mar. 31, 2019	(89,580)								$ 2		(10,554)				(79,027)
Beginning balance, Shares at Mar. 31, 2019		26,657,769
Beginning balance at Mar. 31, 2019		$ 158,414
Beginning balance, Shares at Mar. 31, 2019									12,292,173
Net loss	(28,627)														(28,627)
Issuance of common stock under employee stock compensation plans	37										37
Issuance of common stock under employee stock compensation plans, Shares									34,800
Issuance of preferred stock for cash net of issuance costs, Shares			5,502,950
Issuance of preferred stock for cash net of issuance costs			$ 55,896
Stock-based compensation expense	607										607
Change in unrealized gain (loss) on marketable securities	5													5
Ending balance at Jun. 30, 2019	(117,558)								$ 2		(9,910)			5	(107,654)
Ending balance, Shares at Jun. 30, 2019		32,160,719
Ending balance at Jun. 30, 2019		$ 214,310
Ending balance, Shares at Jun. 30, 2019									12,326,973
Net loss	(20,954)														(20,954)
Issuance of common stock for acquisition of Vindico	10,596										10,596
Issuance of common stock for acquisition of Vindico, Shares									866,149
Issuance of preferred stock for cash net of issuance costs, Shares			774,066
Issuance of preferred stock for cash net of issuance costs			$ 7,863
Stock-based compensation expense	676										676
Change in unrealized gain (loss) on marketable securities	(8)													(8)
Ending balance at Sep. 30, 2019	(127,248)								$ 2		1,362			(3)	(128,608)
Ending balance, Shares at Sep. 30, 2019		32,934,785
Ending balance at Sep. 30, 2019		$ 222,173
Ending balance, Shares at Sep. 30, 2019									13,193,122
Beginning balance at Dec. 31, 2019	$ (149,511)							111	$ 2		2,689			19	(152,221)	111
Beginning balance, Shares at Dec. 31, 2019	32,934,785	32,934,785	14,734,774
Beginning balance at Dec. 31, 2019	$ 222,173	$ 222,173	$ 149,713
Beginning balance, Shares at Dec. 31, 2019									13,196,419
Net loss	$ (28,784)														(28,784)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Issuance of common stock under employee stock compensation plans	$ 183										183
Issuance of common stock under employee stock compensation plans, Shares									174,359
Stock-based compensation expense	1,509										1,509
Change in unrealized gain (loss) on marketable securities	111													111
Ending balance at Mar. 31, 2020	(176,381)								$ 2		4,381			130	(180,894)
Ending balance, Shares at Mar. 31, 2020		32,934,785
Ending balance at Mar. 31, 2020		$ 222,173
Ending balance, Shares at Mar. 31, 2020									13,370,778
Beginning balance at Dec. 31, 2019	$ (149,511)							$ 111	$ 2		2,689			19	(152,221)	$ 111
Beginning balance, Shares at Dec. 31, 2019	32,934,785	32,934,785	14,734,774
Beginning balance at Dec. 31, 2019	$ 222,173	$ 222,173	$ 149,713
Beginning balance, Shares at Dec. 31, 2019									13,196,419
Net loss	(93,627)
Ending balance at Sep. 30, 2020	$ 295,836								$ 6		541,605			(39)	(245,736)
Ending balance, Shares at Sep. 30, 2020	0
Ending balance at Sep. 30, 2020		$ 0
Ending balance, Shares at Sep. 30, 2020									61,819,509
Beginning balance at Mar. 31, 2020	$ (176,381)								$ 2		4,381			130	(180,894)
Beginning balance, Shares at Mar. 31, 2020		32,934,785
Beginning balance at Mar. 31, 2020		$ 222,173
Beginning balance, Shares at Mar. 31, 2020									13,370,778
Net loss	(30,428)														(30,428)
Issuance of preferred stock for cash net of issuance costs, Shares				10,018,300
Issuance of preferred stock for cash net of issuance costs				$ 104,140
Stock-based compensation expense	1,616										1,616
Change in unrealized gain (loss) on marketable securities	(110)													(110)
Ending balance at Jun. 30, 2020	(205,303)								$ 2		5,997			20	(211,322)
Ending balance, Shares at Jun. 30, 2020		42,953,085
Ending balance at Jun. 30, 2020		$ 326,313
Ending balance, Shares at Jun. 30, 2020									13,370,778
Net loss	(34,414)														(34,414)
Issuance of common stock under employee stock compensation plans	3										3
Issuance of common stock under employee stock compensation plans, Shares									3,623
Issuance of common stock for conversion of preferred stock in closing of IPO						$ 326,313				$ 3			$ 326,310
Conversion of preferred stock shares for common stock							(42,953,085)
Conversion of preferred stock value for common stock							$ (326,313)
Issuance of common stock for conversion of preferred stock in closing of IPO, Shares										34,445,108
Issuance of common stock from initial public offering	205,743								$ 1		205,742
Issuance of common stock from initial public offering, Shares									14,000,000
Stock-based compensation expense	1,895										1,895
Reclassification of warrants					$ 1,658							$ 1,658
Change in unrealized gain (loss) on marketable securities	(59)													(59)
Ending balance at Sep. 30, 2020	$ 295,836								$ 6		$ 541,605			$ (39)	$ (245,736)
Ending balance, Shares at Sep. 30, 2020	0
Ending balance at Sep. 30, 2020		$ 0
Ending balance, Shares at Sep. 30, 2020									61,819,509