Unaudited Condensed Statements of Changes in Stockholders' Deficit - USD ($) $ in Thousands	Equity Line of Credit [Member] Preferred Stock [Member] Series A Convertible Preferred Stock [Member]	Equity Line of Credit [Member] Preferred Stock [Member] Series B-1 Convertible Preferred Stock [Member]	Equity Line of Credit [Member] Preferred Stock [Member] Series B-2 Convertible Preferred Stock [Member]	Equity Line of Credit [Member] Undesignated Preferred Stock [Member]	Equity Line of Credit [Member] Common Stock [Member]	Equity Line of Credit [Member] Additional Paid-in Capital [Member]	Equity Line of Credit [Member] Retained Earnings [Member]	Equity Line of Credit [Member]	Optional Exchange Principal Amount [Member] Preferred Stock [Member] Series A Convertible Preferred Stock [Member]	Optional Exchange Principal Amount [Member] Preferred Stock [Member] Series B-1 Convertible Preferred Stock [Member]	Optional Exchange Principal Amount [Member] Preferred Stock [Member] Series B-2 Convertible Preferred Stock [Member]	Optional Exchange Principal Amount [Member] Undesignated Preferred Stock [Member]	Optional Exchange Principal Amount [Member] Common Stock [Member]	Optional Exchange Principal Amount [Member] Additional Paid-in Capital [Member]	Optional Exchange Principal Amount [Member] Retained Earnings [Member]	Optional Exchange Principal Amount [Member]	Preferred Stock [Member] Series A Convertible Preferred Stock [Member]	Preferred Stock [Member] Series B-1 Convertible Preferred Stock [Member]	Preferred Stock [Member] Series B-2 Convertible Preferred Stock [Member]	Undesignated Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2018																					$ 3	$ 154,623	$ (221,192)	$ (66,566)
Net loss																							(12,291)	(12,291)
Stock-based compensation expense																						1,290		1,290
Issuance of common stock						$ 2,721		$ 2,721
Deferred offering costs																						10		10
Balance at Mar. 31, 2019																					3	158,644	(233,483)	(74,836)
Balance at Dec. 31, 2018																					3	154,623	(221,192)	(66,566)
Net loss																								(21,548)
Balance at Jun. 30, 2019																					3	161,190	(242,740)	(81,547)
Balance at Mar. 31, 2019																					3	158,644	(233,483)	(74,836)
Net loss																							(9,257)	(9,257)
Stock-based compensation expense																						1,317		1,317
Issuance of common stock						1,229		1,229
Balance at Jun. 30, 2019																					3	161,190	(242,740)	(81,547)
Balance at Dec. 31, 2019																					4	171,254	(245,714)	(74,456)
Net loss																							(5,754)	(5,754)
Stock-based compensation expense																						1,029		1,029
Issuance of common stock						1,112		1,112					$ 2	$ 9,598		$ 9,600
Deferred offering costs						121		121
Offering expenses charged to equity																						(327)		(327)
Balance at Mar. 31, 2020																					6	182,787	(251,468)	(68,675)
Balance at Dec. 31, 2019																					4	171,254	(245,714)	(74,456)
Net loss																								(4,895)
Balance at Jun. 30, 2020																					7	187,739	(250,609)	(62,863)
Balance at Mar. 31, 2020																					6	182,787	(251,468)	(68,675)
Net loss																							859	859
Stock-based compensation expense																						620		620
Issuance of common stock						$ 1,191		$ 1,191					$ 1	$ 3,149		$ 3,150
Offering expenses charged to equity																						(92)		(92)
Issuance of common stock in exchange for consulting services																						84		84
Balance at Jun. 30, 2020																					$ 7	$ 187,739	$ (250,609)	$ (62,863)