Consolidated Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Preferred Stock [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Preferred Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]	Placement Agents' Designees [Member] Common Stock [Member]	Placement Agents' Designees [Member] Additional Paid-in Capital [Member]	Placement Agents' Designees [Member] Retained Earnings [Member]	Placement Agents' Designees [Member]	Underwriters' Designees [Member] The September 2019 Offering [Member] Common Stock [Member]	Underwriters' Designees [Member] The September 2019 Offering [Member] Additional Paid-in Capital [Member]	Underwriters' Designees [Member] The September 2019 Offering [Member] Retained Earnings [Member]	Underwriters' Designees [Member] The September 2019 Offering [Member]	Underwriters' Designees [Member] The April 2019 Offering [Member] Common Stock [Member]	Underwriters' Designees [Member] The April 2019 Offering [Member] Additional Paid-in Capital [Member]	Underwriters' Designees [Member] The April 2019 Offering [Member] Retained Earnings [Member]	Underwriters' Designees [Member] The April 2019 Offering [Member]	Underwriters' Designees [Member] The March 2020 Offering [Member] Common Stock [Member]	Underwriters' Designees [Member] The March 2020 Offering [Member] Additional Paid-in Capital [Member]	Underwriters' Designees [Member] The March 2020 Offering [Member] Retained Earnings [Member]	Underwriters' Designees [Member] The March 2020 Offering [Member]	The September 2019 Offering [Member] Common Stock [Member]	The September 2019 Offering [Member] Additional Paid-in Capital [Member]	The September 2019 Offering [Member] Retained Earnings [Member]	The September 2019 Offering [Member]	The April 2019 Offering [Member] Common Stock [Member]	The April 2019 Offering [Member] Additional Paid-in Capital [Member]	The April 2019 Offering [Member] Retained Earnings [Member]	The April 2019 Offering [Member]	The March 2020 Offering [Member] Common Stock [Member]	The March 2020 Offering [Member] Additional Paid-in Capital [Member]	The March 2020 Offering [Member] Retained Earnings [Member]	The March 2020 Offering [Member]	The July 2020 Offering [Member] Common Stock [Member]	The July 2020 Offering [Member] Additional Paid-in Capital [Member]	The July 2020 Offering [Member] Retained Earnings [Member]	The July 2020 Offering [Member]	The December 2020 Offering [Member] Common Stock [Member]	The December 2020 Offering [Member] Additional Paid-in Capital [Member]	The December 2020 Offering [Member] Retained Earnings [Member]	The December 2020 Offering [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balances (in shares) at Dec. 31, 2017																																															1,221,064	138,492
Balances at Dec. 31, 2017																																																	$ 41,260	$ (79,982)	$ (38,722)
Issuance of common stock upon conversion of convertible promissory notes, related parties (in shares)																																																1,571,702
Issuance of common stock upon conversion of convertible promissory notes, related parties																																																	35,577		35,577
Issuance of common stock upon conversion of convertible preferred stock (in shares)																																															(1,221,064)	1,918,543
Issuance of common stock upon conversion of convertible preferred stock
Reclassification of warrant to equity																																																	70		70
Issuance of common stock upon reverse merger (in shares)																																																3,510,439
Issuance of common stock upon reverse merger																																																$ 1	31,767		$ 31,768
Issuance of common stock upon exercise of stock options (in shares)																																																2,013			2,013
Issuance of common stock upon exercise of stock options																																																	13		$ 13
Stock-based compensation																																																	539		539
Net loss																																																		(18,007)	(18,007)
Issuance of common stock warrants to placement agents’ designees																																																	70		70
Balances (in shares) at Dec. 31, 2018		7,141,189																																														7,141,189
Balances at Dec. 31, 2018		$ 1	$ 109,226	$ (98,016)	$ 11,211				$ (27)	$ (27)																																						$ 1	109,226	(97,989)	$ 11,238
Reclassification of warrant to equity												$ 100		$ 100		$ 333		$ 333		$ 497		$ 497
Issuance of common stock upon exercise of stock options (in shares)																																																			0
Stock-based compensation																																																	627		$ 627
Net loss																																																		(18,645)	(18,645)
Issuance of common stock, net of offering costs (in shares)																																																1,200,000
Issuance of common stock, net of offering costs																																																	2,440		2,440
Issuance of common stock warrants to placement agents’ designees												$ 100		$ 100		$ 333		$ 333		$ 497		$ 497
Issuance of common stock, pre-funded warrants and common stock warrants, net of offering costs (in shares)																											925,455				26,124,828
Issuance of common stock, pre-funded warrants and common stock warrants, net of offering costs																												$ 7,741		$ 7,741	$ 3	$ 7,239		$ 7,242
Issuance of common stock upon exercise of pre-funded warrants (in shares)																																																12,265,455
Issuance of common stock upon exercise of pre-funded warrants																																																$ 1	1,225		1,226
Issuance of common stock upon exercise of common stock warrants (in shares)																																																598,067
Issuance of common stock upon exercise of common stock warrants																																																	180		180
Balances (in shares) at Dec. 31, 2019																																																48,254,994
Balances at Dec. 31, 2019																																																$ 5	129,608	(116,661)	$ 12,952
Reclassification of warrant to equity																								$ 453		$ 453
Issuance of common stock upon exercise of stock options (in shares)																																																414,676			414,676
Issuance of common stock upon exercise of stock options																																																	602		$ 602
Stock-based compensation																																																	4,358		4,358
Net loss																																																		(32,220)	(32,220)
Issuance of common stock, net of offering costs (in shares)																																							12,503,806				692,651
Issuance of common stock, net of offering costs																																							$ 1	$ 97,033		$ 97,034		$ 4,900		$ 4,900
Issuance of common stock warrants to placement agents’ designees																								$ 453		$ 453
Issuance of common stock, pre-funded warrants and common stock warrants, net of offering costs (in shares)																																			4,000,000
Issuance of common stock, pre-funded warrants and common stock warrants, net of offering costs																																				$ 8,722		$ 8,722
Issuance of common stock upon exercise of common stock warrants (in shares)																																																44,404,966
Issuance of common stock upon exercise of common stock warrants																																																$ 5	25,946		25,951
Disgorgement of short-swing profits, net of costs																																																	652		652
Balances (in shares) at Dec. 31, 2020																																																110,271,093
Balances at Dec. 31, 2020																																																$ 11	$ 272,274	$ (148,881)	$ 123,404