Statements of Stockholders' Equity - USD ($)	Common Stock [Member]	Additional Paid-in Capital	Accumulated Deficit	Total
Beginning Balance at Dec. 31, 2018	$ 11,000	$ 176,228,000	$ (171,003,000)	$ 5,236,000
Beginning Balance, shares at Dec. 31, 2018	110,942,000
Issuance of common stock for services	$ 0	60,000	0	60,000
Issuance of common stock for services (Shares)	136,000
Stock-based compensation, net of forfeitures	$ 0	28,000	0	28,000
Warrants exercised, net	$ 0	20,000	0	20,000
Warrants exercised, net (Shares)	50,000
Net (loss) income	$ 0	0	(5,812,000)	(5,812,000)
Ending Balance at Mar. 31, 2019	$ 11,000	176,336,000	(176,815,000)	(468,000)
Ending Balance, shares at Mar. 31, 2019	111,128,000
Beginning Balance at Dec. 31, 2018	$ 11,000	176,228,000	(171,003,000)	5,236,000
Beginning Balance, shares at Dec. 31, 2018	110,942,000
Net (loss) income				(5,391,000)
Ending Balance at Jun. 30, 2019	$ 14,000	187,491,000	(176,394,000)	11,111,000
Ending Balance, shares at Jun. 30, 2019	142,208,000
Beginning Balance at Mar. 31, 2019	$ 11,000	176,336,000	(176,815,000)	(468,000)
Beginning Balance, shares at Mar. 31, 2019	111,128,000
Stock-based compensation, net of forfeitures	$ 0	73,000	0	73,000
Warrants exercised, net	$ 0	330,000	0	330,000
Warrants exercised, net (Shares)	825,000
Issuance of common stock in connection with the public offering	$ 3,000	11,997,000	0	12,000,000
Issuance of common stock in connection with the public offering (in shares)	30,000,000
Issuance of common stock in connection with the equity distribution agreement	$ 0	142,000	0	142,000
Issuance of common stock in connection with the equity distribution agreement (in shares)	255,000
Offering costs related to the issuance of common stock in connection with the equity distribution agreement	$ 0	(144,000)	0	(144,000)
Offering costs related to the issuance of common stock in connection with the public offering	0	(1,243,000)	0	(1,243,000)
Net (loss) income	0	0	421,000	421,000
Ending Balance at Jun. 30, 2019	$ 14,000	187,491,000	(176,394,000)	11,111,000
Ending Balance, shares at Jun. 30, 2019	142,208,000
Beginning Balance at Dec. 31, 2019	$ 16,000	191,060,000	(184,633,000)	6,443,000
Beginning Balance, shares at Dec. 31, 2019	158,645,000
Issuance of common stock for services	$ 0	80,000	0	80,000
Issuance of common stock for services (Shares)	136,000
Stock-based compensation, net of forfeitures	$ 0	213,000	0	213,000
Issuance of common stock in connection with the Sales Agreement	$ 0	682,000	0	682,000
Issuance of common stock in connection with the Sales Agreement (in shares)	1,241,000
Offering costs related to the issuance of common stock in connection with the Sales Agreement	$ 0	(246,000)	0	(246,000)
Net (loss) income	0	0	(5,179,000)	(5,179,000)
Ending Balance at Mar. 31, 2020	$ 16,000	191,789,000	(189,812,000)	1,993,000
Ending Balance, shares at Mar. 31, 2020	160,022,000
Beginning Balance at Dec. 31, 2019	$ 16,000	191,060,000	(184,633,000)	$ 6,443,000
Beginning Balance, shares at Dec. 31, 2019	158,645,000
Stock options exercised, net (Shares)				10,000
Net (loss) income				$ (7,910,000)
Ending Balance at Jun. 30, 2020	$ 17,000	198,869,000	(192,543,000)	6,343,000
Ending Balance, shares at Jun. 30, 2020	173,342,000
Beginning Balance at Mar. 31, 2020	$ 16,000	191,789,000	(189,812,000)	1,993,000
Beginning Balance, shares at Mar. 31, 2020	160,022,000
Stock-based compensation, net of forfeitures	$ 0	64,000	0	64,000
Stock options exercised, net	$ 0	0	0	0
Stock options exercised, net (Shares)	1,000
Warrants exercised, net	$ 0	100,000	0	100,000
Warrants exercised, net (Shares)	250,000
Issuance of common stock in connection with the Sales Agreement	$ 1,000	7,230,000	0	7,231,000
Issuance of common stock in connection with the Sales Agreement (in shares)	13,069,000
Offering costs related to the issuance of common stock in connection with the Sales Agreement	$ 0	(314,000)	0	(314,000)
Net (loss) income	0	0	(2,731,000)	(2,731,000)
Ending Balance at Jun. 30, 2020	$ 17,000	$ 198,869,000	$ (192,543,000)	$ 6,343,000
Ending Balance, shares at Jun. 30, 2020	173,342,000