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																								(18,485)
Balance at Sep. 30, 2019																					3	169,054	(239,677)	(70,620)
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)
Net loss																							3,063	3,063
Stock-based compensation expense																						1,057		1,057
Issuance of common stock						1,496		1,496
Balance at Sep. 30, 2019																					3	169,054	(239,677)	(70,620)
Issuance of common stock in connection with conversion of principal on 2021 Notes																						3,000		3,000
Change in fair value of embedded conversion feature in connection with debt modification																						2,311		2,311
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																								(7,904)
Balance at Sep. 30, 2020																					7	191,284	(253,618)	(62,327)
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)
Net loss																							(3,009)	(3,009)
Stock-based compensation expense																						385		385
Issuance of common stock														$ 3,113		$ 3,113
Issuance of common stock in exchange for consulting services																						47		47
Balance at Sep. 30, 2020																					$ 7	$ 191,284	$ (253,618)	$ (62,327)