Financing (Details 10) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Debt Conversion [Line Items]
Beginning balance, December 31, 2012			$ 70,126
Fair value adjustments:
Compound embedded derivatives	(1,849)	75,351	(2,149)	(14,298)
Warrant derivatives	289	42,409	3,411	921
Hybrid instruments	(29,569)	36,773	(22,795)	5,603
Conversions:
Series C Preferred Stock			(10)
August 24, 2006 financing			(644)
December 29, 2006 financing			(503)
March 27, 2007 financing			(242)
April 11, 2008 financing			(71)
July 29, 2008 financing			(234)
July 15, 2009 financing			(823)
August 14, 2009 financing			(475)
February 8, 2011 financing			(28)
April 13, 2011 financing			(199)
October 25, 2011 financing			(37)
December 8, 2011 financing			(217)
March 26, 2012 financing			(141)
June 1, 2012 financing			(567)
Ending balance, June 30, 2013	87,468		87,468
Embedded Derivative Financial Instruments [Member]
Debt Conversion [Line Items]
Beginning balance, December 31, 2012			2,147
Fair value adjustments:
Compound embedded derivatives			2,149
Warrant derivatives			0
Hybrid instruments			0
Conversions:
Series C Preferred Stock			(10)
August 24, 2006 financing			0
December 29, 2006 financing			0
March 27, 2007 financing			0
April 11, 2008 financing			0
July 29, 2008 financing			0
July 15, 2009 financing			0
August 14, 2009 financing			0
February 8, 2011 financing			0
April 13, 2011 financing			0
October 25, 2011 financing			0
December 8, 2011 financing			0
March 26, 2012 financing			0
June 1, 2012 financing			0
Ending balance, June 30, 2013	4,286		4,286
Warrant [Member]
Debt Conversion [Line Items]
Beginning balance, December 31, 2012			3,687
Fair value adjustments:
Compound embedded derivatives			0
Warrant derivatives			(3,411)
Hybrid instruments			0
Conversions:
Series C Preferred Stock			0
August 24, 2006 financing			0
December 29, 2006 financing			0
March 27, 2007 financing			0
April 11, 2008 financing			0
July 29, 2008 financing			0
July 15, 2009 financing			0
August 14, 2009 financing			0
February 8, 2011 financing			0
April 13, 2011 financing			0
October 25, 2011 financing			0
December 8, 2011 financing			0
March 26, 2012 financing			0
June 1, 2012 financing			0
Ending balance, June 30, 2013	276		276
Hybrid Instrument [Member]
Debt Conversion [Line Items]
Beginning balance, December 31, 2012			64,292
Fair value adjustments:
Compound embedded derivatives			0
Warrant derivatives			0
Hybrid instruments			22,795
Conversions:
Series C Preferred Stock			0
August 24, 2006 financing			(644)
December 29, 2006 financing			(503)
March 27, 2007 financing			(242)
April 11, 2008 financing			(71)
July 29, 2008 financing			(234)
July 15, 2009 financing			(823)
August 14, 2009 financing			(475)
February 8, 2011 financing			(28)
April 13, 2011 financing			(199)
October 25, 2011 financing			(37)
December 8, 2011 financing			(217)
March 26, 2012 financing			(141)
June 1, 2012 financing			(567)
Ending balance, June 30, 2013	$ 82,906		$ 82,906