Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets
Property and equipment, accumulated depreciation (in dollars)	$ 332	$ 308
Patents, accumulated amortization (in dollars)	$ 267	$ 0
Stockholders' equity
Series I redeemable preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Series I redeemable preferred stock, shares issued	119,760	119,760
Series I redeemable preferred stock, shares outstanding	119,760	119,760
Series I redeemable preferred stock, liquidation preference	$ 167	$ 167
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	3,770,113	814,114
Common stock, shares outstanding	3,769,712	813,713
Treasury stock, shares	401	401
Series A Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
liquidation preference	$ 0.0001	$ 0.0001
Series B Convertible Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	1	1
Preferred stock, shares outstanding	1	1
liquidation preference	$ 0.0001	$ 0.0001
Series C Convertible Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	1	0
Preferred stock, shares outstanding	1	0
liquidation preference	$ 0.0001	$ 0.0001
Series D Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	227,582	0
Preferred stock, shares outstanding	227,582	0
liquidation preference	$ 0.0001	$ 0.0001
Series D-1 Convertible Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	59,265	0
Preferred stock, shares outstanding	59,265	0
liquidation preference	$ 0.0001	$ 0.0001
Series E Convertible Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
liquidation preference	$ 0.0001	$ 0.0001
Series F Convertible Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
liquidation preference	$ 0.0001	$ 0.0001
Series F-1 Convertible Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	156,250	0
Preferred stock, shares outstanding	156,250	0
liquidation preference	$ 0.0001	$ 0.0001
Series H Convertible Preferred Stock [Member]
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.0001
Preferred stock, shares issued	459,043	0
Preferred stock, shares outstanding	459,043	0
liquidation preference	$ 0.0001	$ 0.0001