Convertible Preferred Stock (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Series A Preferred Stock [Member]	Jun. 30, 2012 Series B-1 Preferred Stock [Member]	Jun. 30, 2012 Series B-2 Preferred Stock [Member]	Jun. 30, 2012 Series C Preferred Stock [Member]	Jun. 30, 2012 Series D Preferred Stock [Member]	Jun. 30, 2012 Series E Preferred Stock [Member]	May 31, 2012 Series E Preferred Stock [Member]
Convertible Preferred Stock (Textual) [Abstract]
Convertible preferred stock, shares issued	42,954,843		1,527,611	3,425,152	14,672,434	6,944,450	11,385,196	5,955,881	5,955,881
Preferred Stock, issued per share amount								$ 3.40
Carrying Value	$ 102,023	$ 83,178	$ 1,835	$ 4,726	$ 21,039	$ 19,905	$ 35,673	$ 18,845
Redemption amount of outstanding shares			$ 1.44	$ 1.44	$ 1.44	$ 2.88	$ 3.25	$ 3.40