Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($)	Redeemable Convertible Preferred Stock Series B [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Total
Balances at Dec. 31, 2014	$ 1,990,000	$ 40,000	$ 365,403,000	$ (362,006,000)	$ 3,437,000
Balances (in shares) at Dec. 31, 2014	8,671,040	3,983,182
Net loss				(516,000)	(516,000)
Accretion of dividends on Series B redeemable convertible preferred stock	$ 1,307,000		(1,307,000)		(1,307,000)
Accretion to redemption value of Series B redeemable convertible stock	8,971,000		(8,971,000)		(8,971,000)
Conversion of Series B redeemable convertible preferred stock to common stock, value	$ (378,000)	$ 2,000	1,504,000		1,506,000
Conversion of Series B redeemable convertible preferred stock to common stock, shares	(1,143,187)	228,637
Common stock issued in March 2015 financing, net of offering costs (value)		$ 16,000	8,250,000		8,266,000
Common stock issued in March 2015 financing, net of offering costs (shares)		1,575,758
Warrants exercised		$ 1,000	1,072,000		1,073,000
Warrants exercised (in shares)		56,645
Warrants reclassified from liabilities to equity due to amendment of warrants			5,462,000		5,462,000
Warrants reclassified from liabilities to equity due to increase in authorized shares			3,281,000		3,281,000
Exercise of common stock options and other (in shares)		39,281
Stock-based compensation			479,000		479,000
Stock-based compensation - severance			4,000		4,000
Balances at Dec. 31, 2015	$ 11,890,000	$ 59,000	375,177,000	(362,522,000)	12,714,000
Balances (in shares) at Dec. 31, 2015	7,527,853	5,883,503
Net loss				(3,112,000)	(3,112,000)
Accretion of dividends on Series B redeemable convertible preferred stock	$ 323,000		(323,000)		(323,000)
Accretion to redemption value of Series B redeemable convertible stock	1,402,000		(1,402,000)		(1,402,000)
Warrants issued (value)			204,000		$ 204,000
Exercise of common stock options and other (in shares)
Stock-based compensation			816,000		$ 816,000
Balances at Mar. 31, 2016	$ 13,615,000	$ 59,000	$ 374,472,000	$ (365,634,000)	$ 8,897,000
Balances (in shares) at Mar. 31, 2016	7,527,853	5,883,503