CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at Dec. 31, 2018	$ 13	$ 172,988	$ (9)	$ (90,109)	$ 82,883
Balance (in shares) at Dec. 31, 2018	13,124,842
Stock-based compensation expense		1,177			1,177
Exercise of stock options		40			40
Exercise of stock options (in shares)	9,696
Unrealized gain (loss) on investments held			63		63
Net loss				(26,323)	(26,323)
Balance at Jun. 30, 2019	$ 13	174,205	54	(116,432)	57,840
Balance (in shares) at Jun. 30, 2019	13,134,538
Balance at Mar. 31, 2019	$ 13	173,577	34	(103,050)	70,574
Balance (in shares) at Mar. 31, 2019	13,127,128
Stock-based compensation expense		599			599
Exercise of stock options		29			29
Exercise of stock options (in shares)	7,410
Unrealized gain (loss) on investments held			20		20
Net loss				(13,382)	(13,382)
Balance at Jun. 30, 2019	$ 13	174,205	54	(116,432)	57,840
Balance (in shares) at Jun. 30, 2019	13,134,538
Balance at Dec. 31, 2019	$ 13	176,103		(133,959)	42,157
Balance (in shares) at Dec. 31, 2019	13,291,563
Stock-based compensation expense		1,535			1,535
Issuance of common stock in Private Placement, net of issuance costs	$ 14	34,243			34,257
Issuance of common stock in Private Placement, net of issuance costs (in shares)	14,000,000
Net loss				(28,662)	(28,662)
Balance at Jun. 30, 2020	$ 27	211,881		(162,621)	49,287
Balance (in shares) at Jun. 30, 2020	27,291,563
Balance at Mar. 31, 2020	$ 13	176,888	28	(149,225)	27,704
Balance (in shares) at Mar. 31, 2020	13,291,563
Stock-based compensation expense		750			750
Issuance of common stock in Private Placement, net of issuance costs	$ 14	34,243			34,257
Issuance of common stock in Private Placement, net of issuance costs (in shares)	14,000,000
Unrealized gain (loss) on investments held			$ (28)		(28)
Net loss				(13,396)	(13,396)
Balance at Jun. 30, 2020	$ 27	$ 211,881		$ (162,621)	$ 49,287
Balance (in shares) at Jun. 30, 2020	27,291,563