Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Placement Agents' Designees [Member] Preferred Stock [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 April 2019 Offering [Member] Preferred Stock [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 September 2019 Offering [Member] Preferred Stock [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]	The April 2019 Offering [Member] Preferred Stock [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 September 2019 Offering [Member] Preferred Stock [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]	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																										$ 1		$ 41,259	$ (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																											$ 157	35,420		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																										$ (1)	$ 192	(191)
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																											$ 365	31,403		$ 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																												70		70
Balances (in shares) at Dec. 31, 2018																											7,141,189
Balances at Dec. 31, 2018																											$ 714	108,513	(97,989)	11,238
Reclassification of warrant to equity			$ 100		$ 100			$ 333		$ 333			$ 497		$ 497
Stock-based compensation																												627		627
Net loss																													(18,645)	(18,645)
Cumulative effect of adoption of new leases standard at Dec. 31, 2018																													(27)	(27)
Balances as of January 1, 2019, as adjusted at Dec. 31, 2018																											$ 714	108,513	(98,016)	11,211
Issuance of common stock, net of offering costs (in shares)																											1,200,000
Issuance of common stock, net of offering costs																											$ 120	2,320		2,440
Issuance of common stock warrants			$ 100		$ 100			$ 333		$ 333			$ 497		$ 497
Issuance of common stock and warrants, net of offering costs (in shares)																	925,455					26,124,828
Issuance of common stock and warrants, net of offering costs																	$ 93	$ 7,648		$ 7,741		$ 2,612	$ 4,630		$ 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																											$ 1,226			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																											$ 60	120		180
Balances (in shares) at Dec. 31, 2019																											48,254,994
Balances at Dec. 31, 2019																											$ 4,825	$ 124,788	$ (116,661)	$ 12,952