Fair Value of Financial Instruments (Details 1) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Liabilities measured at estimated fair value using unobservable inputs
Beginning balance	$ 15,270	$ 6,102
Adjustments to estimated fair value	(2,696)	(3,346)
Decrease of the embedded derivative liabilities for preferred shares converted into common stock		(315)
Ending balance	12,717	2,372
Series C-1 Preferred Stock [Member]
Liabilities measured at estimated fair value using unobservable inputs
Forfeited accrued dividends payable in Series C-12 Preferred		(72)
Accrued dividends payable in Series C-1 Preferred	143	3
Embedded Derivative [Member]
Liabilities measured at estimated fair value using unobservable inputs
Beginning balance	3,680	5,170
Adjustments to estimated fair value	77	(1,620)
Decrease of the embedded derivative liabilities for preferred shares converted into common stock		(315)
Ending balance	3,900	3,166
Embedded Derivative [Member] | Series C-1 Preferred Stock [Member]
Liabilities measured at estimated fair value using unobservable inputs
Forfeited accrued dividends payable in Series C-12 Preferred		(72)
Accrued dividends payable in Series C-1 Preferred	143	3
Warrant Derivative [Member]
Liabilities measured at estimated fair value using unobservable inputs
Beginning balance	11,590	932
Adjustments to estimated fair value	(2,773)	(1,726)
Decrease of the embedded derivative liabilities for preferred shares converted into common stock
Ending balance	8,817	(794)
Warrant Derivative [Member] | Series C-1 Preferred Stock [Member]
Liabilities measured at estimated fair value using unobservable inputs
Forfeited accrued dividends payable in Series C-12 Preferred
Accrued dividends payable in Series C-1 Preferred