Financing (Details 9) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Debt Conversion [Line Items]
Beginning balance, December 31, 2012:			$ 70,126
Fair value adjustments:
Compound embedded derivatives	2,620	(1,036)	4,769	13,262
Warrant derivatives	(92)	(4,897)	(3,503)	(5,818)
Hybrid instruments	24,165	(6,353)	46,959	(11,958)
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)
October 18, 2008 financing			(23)
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)
February 6, 2012 financing			(29)
March 26, 2012 financing			(141)
June 1, 2012 financing			(567)
Ending balance, September 30, 2013	114,107		114,107
Embedded Derivative Financial Instruments [Member]
Debt Conversion [Line Items]
Beginning balance, December 31, 2012:			2,147
Fair value adjustments:
Compound embedded derivatives			4,768
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
October 18, 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
February 6, 2012 financing			0
March 26, 2012 financing			0
June 1, 2012 financing			0
Ending balance, September 30, 2013	6,905		6,905
Warrant [Member]
Debt Conversion [Line Items]
Beginning balance, December 31, 2012:			3,687
Fair value adjustments:
Compound embedded derivatives			0
Warrant derivatives			(3,503)
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
October 18, 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
February 6, 2012 financing			0
March 26, 2012 financing			0
June 1, 2012 financing			0
Ending balance, September 30, 2013	184		184
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			46,959
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)
October 18, 2008 financing			(23)
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)
February 6, 2012 financing			(29)
March 26, 2012 financing			(141)
June 1, 2012 financing			(567)
Ending balance, September 30, 2013	$ 107,018		$ 107,018