Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	78,300,000	78,300,000
Common stock, shares issued	3,770,266	3,616,101
Common stock, shares outstanding	3,770,266	3,616,101
Series A Preferred Stock [Member]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	33,188,889	33,188,889
Preferred stock, shares issued	33,188,889	33,188,889
Preferred stock, shares outstanding	33,188,889	33,188,889
Aggregate liquidation preference	$ 41,969	$ 40,973
Series B Preferred Stock [Member]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,190,551	5,190,551
Preferred stock, shares issued	5,190,551	5,190,551
Preferred stock, shares outstanding	5,190,551	5,190,551
Aggregate liquidation preference	10,491	10,232
Series C Preferred Stock [Member]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	15,882,389	15,882,389
Preferred stock, shares issued	15,882,389	15,882,389
Preferred stock, shares outstanding	15,882,389	15,882,389
Aggregate liquidation preference	$ 85,592	$ 83,252