CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' (DEFICIT) EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series A-2 Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2018	$ (13,875)				$ 1,055	$ (2)	$ (14,928)
Temporary equity, shares at Dec. 31, 2018		48,850,000	7,482,515
Temporary equity, balance at Dec. 31, 2018		$ 44,657	$ 10,372
Balance, shares at Dec. 31, 2018				1,135,015
Issuance of Series A-2 Convertible Preferred Stock,net of issuance costs			$ 22,898
Issuance of Series A-2 Convertible Preferred Stock,net of issuance costs, shares			16,083,916
Stock-based compensation	41				41
Exercise of stock options	34				34
Exercise of stock options, shares				35,460
Comprehensive income:
Unrealized gain (loss) on investments	2					2
Net loss	(4,971)						(4,971)
Balance at Mar. 31, 2019	(18,769)				1,130		(19,899)
Temporary equity, shares at Mar. 31, 2019		48,850,000	23,566,431
Temporary equity, balance at Mar. 31, 2019		$ 44,657	$ 33,270
Balance, shares at Mar. 31, 2019				1,170,475
Balance at Dec. 31, 2018	(13,875)				1,055	(2)	(14,928)
Temporary equity, shares at Dec. 31, 2018		48,850,000	7,482,515
Temporary equity, balance at Dec. 31, 2018		$ 44,657	$ 10,372
Balance, shares at Dec. 31, 2018				1,135,015
Comprehensive income:
Net loss	(9,144)
Balance at Jun. 30, 2019	(22,894)				1,170	8	(24,072)
Temporary equity, shares at Jun. 30, 2019		48,850,000	23,566,431
Temporary equity, balance at Jun. 30, 2019		$ 44,657	$ 33,270
Balance, shares at Jun. 30, 2019				1,170,475
Balance at Dec. 31, 2018	$ (13,875)				1,055	(2)	(14,928)
Temporary equity, shares at Dec. 31, 2018		48,850,000	7,482,515
Temporary equity, balance at Dec. 31, 2018		$ 44,657	$ 10,372
Balance, shares at Dec. 31, 2018				1,135,015
Exercise of stock options, shares	69,615
Comprehensive income:
Net loss	$ (19,700)
Balance at Dec. 31, 2019	$ (33,219)				1,428	5	(34,652)
Temporary equity, shares at Dec. 31, 2019	72,416,431	48,850,000	23,566,431
Temporary equity, balance at Dec. 31, 2019	$ 77,927	$ 44,657	$ 33,270
Balance, shares at Dec. 31, 2019				1,204,630
Balance at Mar. 31, 2019	(18,769)				1,130		(19,899)
Temporary equity, shares at Mar. 31, 2019		48,850,000	23,566,431
Temporary equity, balance at Mar. 31, 2019		$ 44,657	$ 33,270
Balance, shares at Mar. 31, 2019				1,170,475
Stock-based compensation	40				40
Comprehensive income:
Unrealized gain (loss) on investments	8					8
Net loss	(4,173)						(4,173)
Balance at Jun. 30, 2019	(22,894)				1,170	8	(24,072)
Temporary equity, shares at Jun. 30, 2019		48,850,000	23,566,431
Temporary equity, balance at Jun. 30, 2019		$ 44,657	$ 33,270
Balance, shares at Jun. 30, 2019				1,170,475
Balance at Dec. 31, 2019	$ (33,219)				1,428	5	(34,652)
Temporary equity, shares at Dec. 31, 2019	72,416,431	48,850,000	23,566,431
Temporary equity, balance at Dec. 31, 2019	$ 77,927	$ 44,657	$ 33,270
Balance, shares at Dec. 31, 2019				1,204,630
Stock-based compensation	129				129
Exercise of stock options	5				5
Exercise of stock options, shares				2,677
Comprehensive income:
Unrealized gain (loss) on investments	23					23
Net loss	(7,738)						(7,738)
Balance at Mar. 31, 2020	(40,800)				1,562	28	(42,390)
Temporary equity, shares at Mar. 31, 2020		48,850,000	23,566,431
Temporary equity, balance at Mar. 31, 2020		$ 44,657	$ 33,270
Balance, shares at Mar. 31, 2020				1,207,307
Balance at Dec. 31, 2019	$ (33,219)				1,428	5	(34,652)
Temporary equity, shares at Dec. 31, 2019	72,416,431	48,850,000	23,566,431
Temporary equity, balance at Dec. 31, 2019	$ 77,927	$ 44,657	$ 33,270
Balance, shares at Dec. 31, 2019				1,204,630
Exercise of stock options, shares	140,073
Comprehensive income:
Net loss	$ (17,211)
Balance at Jun. 30, 2020	$ (50,019)				1,831	13	(51,863)
Temporary equity, shares at Jun. 30, 2020	95,982,862	48,850,000	47,132,862
Temporary equity, balance at Jun. 30, 2020	$ 111,565	$ 44,657	$ 66,908
Balance, shares at Jun. 30, 2020				1,344,704
Balance at Mar. 31, 2020	(40,800)				1,562	28	(42,390)
Temporary equity, shares at Mar. 31, 2020		48,850,000	23,566,431
Temporary equity, balance at Mar. 31, 2020		$ 44,657	$ 33,270
Balance, shares at Mar. 31, 2020				1,207,307
Issuance of Series A-2 Convertible Preferred Stock,net of issuance costs			$ 33,638
Issuance of Series A-2 Convertible Preferred Stock,net of issuance costs, shares			23,566,431
Stock-based compensation	120				120
Exercise of stock options	149				149
Exercise of stock options, shares				137,397
Comprehensive income:
Unrealized gain (loss) on investments	(15)					(15)
Net loss	(9,473)						(9,473)
Balance at Jun. 30, 2020	$ (50,019)				$ 1,831	$ 13	$ (51,863)
Temporary equity, shares at Jun. 30, 2020	95,982,862	48,850,000	47,132,862
Temporary equity, balance at Jun. 30, 2020	$ 111,565	$ 44,657	$ 66,908
Balance, shares at Jun. 30, 2020				1,344,704