Summary of Significant Accounting Policies (Details)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Stock options	12,850,141	3,005,532	2,726,137
Warrants issued in connection with Secured Promissory Notes	492,620		87,720
Warrants issued in connection with recap	34,436,447		0
Other outstanding warrants	759,287		780,787
Potentially dilutive securities outstanding	55,339,893		22,724,217
Series D Convertible Preferred Stock Warrants [Member]
Preferred stock, shares outstanding	3,388,677		3,388,677
Conversion Of Preferred Stock	0		6,358,872
Series E Convertible Preferred Stock Warrants [Member]
Preferred stock, shares outstanding	3,412,721		3,127,344
Conversion Of Preferred Stock	0		6,254,680