Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Underwriters' Designees [Member] Common Stock [Member]	Underwriters' Designees [Member] Additional Paid-in Capital [Member]	Underwriters' Designees [Member] Retained Earnings [Member]	Underwriters' Designees [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]	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]	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]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balances (in shares) at Dec. 31, 2018													7,141,189,000				7,141,189
Balances at Dec. 31, 2018											$ (27)	$ (27)	$ 1	$ 109,226	$ (98,016)	$ 11,211	$ 1	$ 109,226	$ (97,989)	$ 11,238
Issuance of common stock upon exercise of common stock warrants																	1	651		$ 652
Issuance of common stock upon exercise of stock options (in shares)																				0
Stock-based compensation																		344		$ 344
Net loss																			(6,976)	(6,976)
Issuance of common stock and common stock warrants, net of offering costs (in shares)																	925,455
Issuance of common stock and common stock warrants, net of offering costs																		7,741		7,741
Issuance of common stock warrants to placement agents’ designees		$ 333		$ 333		$ 100		$ 100
Issuance of common stock upon exercise of pre-funded warrants (in shares)																	6,519,091
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
Balances (in shares) at Jun. 30, 2019																	15,785,735
Balances at Jun. 30, 2019																	$ 2	120,835	(104,992)	15,845
Balances (in shares) at Mar. 31, 2019																	8,341,189
Balances at Mar. 31, 2019																	$ 1	111,930	(99,355)	12,576
Issuance of common stock upon exercise of common stock warrants																	1	651		652
Stock-based compensation																		180		180
Net loss																			(5,637)	(5,637)
Issuance of common stock and common stock warrants, net of offering costs (in shares)																	925,455
Issuance of common stock and common stock warrants, net of offering costs																		7,741		7,741
Issuance of common stock warrants to placement agents’ designees		$ 333		$ 333
Issuance of common stock upon exercise of pre-funded warrants (in shares)																	6,519,091
Balances (in shares) at Jun. 30, 2019																	15,785,735
Balances at Jun. 30, 2019																	$ 2	120,835	(104,992)	15,845
Balances (in shares) at Dec. 31, 2019																	48,254,994
Balances at Dec. 31, 2019																	$ 5	129,608	(116,661)	12,952
Issuance of common stock upon exercise of common stock warrants (in shares)																	43,707,286
Issuance of common stock upon exercise of common stock warrants																	$ 5	24,653		$ 24,658
Issuance of common stock upon exercise of stock options (in shares)																	178,381			178,381
Issuance of common stock upon exercise of stock options																		116		$ 116
Disgorgement of short-swing profits, net of costs																		652		652
Stock-based compensation																		2,956		2,956
Net loss																			(10,274)	(10,274)
Issuance of common stock and common stock warrants, net of offering costs (in shares)																	4,000,000
Issuance of common stock and common stock warrants, net of offering costs																		8,722		8,722
Issuance of common stock warrants to placement agents’ designees						$ 453		$ 453
Balances (in shares) at Jun. 30, 2020																	96,140,661
Balances at Jun. 30, 2020																	$ 10	167,160	(126,935)	40,235
Balances (in shares) at Mar. 31, 2020																	72,004,720
Balances at Mar. 31, 2020																	$ 7	149,244	(117,958)	31,293
Issuance of common stock upon exercise of common stock warrants (in shares)																	23,981,166
Issuance of common stock upon exercise of common stock warrants																	$ 3	14,306		14,309
Issuance of common stock upon exercise of stock options (in shares)																	154,775
Issuance of common stock upon exercise of stock options																		98		98
Disgorgement of short-swing profits, net of costs																		652		652
Stock-based compensation																		2,860		2,860
Net loss																			(8,977)	(8,977)
Balances (in shares) at Jun. 30, 2020																	96,140,661
Balances at Jun. 30, 2020																	$ 10	$ 167,160	$ (126,935)	$ 40,235