Consolidated Statements of Stockholders' Equity - USD ($)	Total	Series B Convertible Preferred Stock [Member]	Series C Convertible Preferred Stock [Member]	Series D Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member] Series B Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member] Series C Convertible Preferred Stock [Member]	Convertible Preferred Stock [Member] Series D Convertible Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member] Series B Convertible Preferred Stock [Member]	Common Stock [Member] Series C Convertible Preferred Stock [Member]	Common Stock [Member] Series D Convertible Preferred Stock [Member]	Capital in Excess of Par Value [Member]	Capital in Excess of Par Value [Member] Series B Convertible Preferred Stock [Member]	Capital in Excess of Par Value [Member] Series C Convertible Preferred Stock [Member]	Capital in Excess of Par Value [Member] Series D Convertible Preferred Stock [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2013	$ 7,306,000								$ 1,000				$ 281,422,000				$ (274,117,000)
Beginning balance, Shares at Dec. 31, 2013					328,925				775,663
Issuance of common stock (net of costs) from exercise of outstanding warrants	4,085,000												4,085,000
Issuance of common stock (net of costs) from exercise of outstanding warrants, Shares									105,965
Stock-based compensation	862,000												862,000
Stock-based compensation, Shares									69,308
Net loss	(8,251,000)																(8,251,000)
Ending balance at Dec. 31, 2014	4,002,000								$ 1,000				286,369,000				(282,368,000)
Ending balance, Shares at Dec. 31, 2014					328,925				950,936
Issuance of common stock (net of costs)	8,890,000								$ 1,000				8,889,000
Issuance of common stock (net of costs), Shares									1,106,319
Issuance of common stock (net of costs) from exercise of outstanding warrants	1,687,000												1,687,000
Issuance of preferred stock		$ 4,305,000												$ 4,305,000
Issuance of common stock (net of costs) from exercise of outstanding warrants, Shares									61,124
Issuance of preferred stock, Shares						4,750
Reclassification of warrant liability upon exercise	669,000												669,000
Repurchase of common shares to satisfy withholding obligations	(27,000)												(27,000)
Repurchase of common shares to satisfy withholding obligations, Shares									(8,926)
Stock-based compensation	2,198,000												2,198,000
Stock-based compensation, Shares									(2,667)
Conversion of preferred stock to common stock										$ 1,000				$ (1,000)
Conversion of preferred stock to common stock, Shares						(2,802)				533,762
Net loss	(8,602,000)																(8,602,000)
Ending balance at Dec. 31, 2015	13,122,000								$ 3,000				304,089,000				(290,970,000)
Ending balance, Shares at Dec. 31, 2015					330,873				2,640,548
Issuance of common stock (net of costs)	3,222,000								$ 2,000				3,220,000
Issuance of common stock (net of costs), Shares									2,092,391
Issuance of preferred stock			$ 1,118,000	$ 6,748,000											$ 1,118,000	$ 6,748,000
Issuance of preferred stock, Shares							1,295	7,587
Stock-based compensation	1,004,000												1,004,000
Cancellation of shares from reverse stock split									(37)
Conversion of preferred stock to common stock												$ 2,000				$ (2,000)
Conversion of preferred stock to common stock, Shares						(1,948)	(1,295)	(2,745)	1,830,000	371,000	419,812	1,830,000
Net loss	(11,116,000)																(11,116,000)
Ending balance at Dec. 31, 2016	$ 14,098,000								$ 7,000				$ 316,177,000				$ (302,086,000)
Ending balance, Shares at Dec. 31, 2016					333,767				7,353,714