Consolidated Statements of Stockholders' Equity - USD ($)	Total	Series D Preferred Stock [Member]	Series E Preferred Stock [Member]	Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member] Series D Preferred Stock [Member]	Convertible Preferred Stock [Member] Series E Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series D Preferred Stock [Member]	Common Stock [Member] Series E Preferred Stock [Member]	Capital in Excess of Par Value [Member]	Capital in Excess of Par Value [Member] Series E Preferred Stock [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2016	$ 14,098,000			$ 0			$ 1,000			$ 316,183,000		$ (302,086,000)
Beginning balance, Shares at Dec. 31, 2016				333,767			735,371
Issuance of common stock (net of costs) from exercise of outstanding warrants	200,000									200,000
Issuance of common stock (net of costs) from exercise of outstanding warrants, Shares							13,333
Conversion of preferred stock to common stock		$ 0
Conversion of preferred stock to common stock, shares					(4,842)			322,788
Stock-based compensation	341,000									341,000
Stock-based compensation, Shares							3,167
Net loss	(9,527,000)											(9,527,000)
Ending balance at Dec. 31, 2017	5,112,000			$ 0			$ 1,000			316,724,000		(311,613,000)
Ending balance, Shares at Dec. 31, 2017				328,925			1,074,659
Issuance of preferred stock, Shares						4,135
Conversion of preferred stock to common stock			$ 0
Conversion of preferred stock to common stock, shares						(2,273)			649,429
Issuance of common stock (net of costs)	9,680,000						$ 2,000			9,678,000
Issuance of common stock (net of costs), Shares							1,509,000
Stock-based compensation	84,000									84,000
Warrant Exercises,Shares							38,720
Cancellation of shares from reverse stock split, Shares							(1,199)
Net loss	(8,131,000)											(8,131,000)
Ending balance at Dec. 31, 2018	6,745,000			$ 0			$ 3,000			326,486,000		(319,744,000)
Ending balance, Shares at Dec. 31, 2018				330,787			3,270,609
Conversion of preferred stock to common stock			$ 0						$ 1,000		$ (1,000)
Conversion of preferred stock to common stock, shares						(1,862)			532,000
Conversion of prefunded warrants to common stock							$ 4,000			(4,000)
Conversion of prefunded warrants to common stock, Shares							3,900,000
Issuance of common stock (net of costs)	3,801,000						$ 10,000			3,791,000
Issuance of common stock (net of costs), Shares							9,634,000
Stock-based compensation	87,000									87,000
Warrant Exercises	99,000									99,000
Warrant Exercises,Shares							395,284
Net loss	(9,229,000)											(9,229,000)
Ending balance at Dec. 31, 2019	$ 1,503,000			$ 0			$ 18,000			$ 330,458,000		$ (328,973,000)
Ending balance, Shares at Dec. 31, 2019				328,925			17,731,893