Financing (Details 7) (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]
Unrealized Gain On Hybrid Instrument	$ (29,569)	$ 37,620	$ (22,795)	$ 6,450
Less: Day-one loss from debenture financings	0	(847)	0	(847)
Gain (loss) from changes in fair value of hybrid instruments	(29,569)	36,773	(22,795)	5,603
Debentures 2006 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	(7,202)	1,734	(5,315)	1,734
Debentures 2007 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	(7,821)	24,068	(5,492)	(989)
Debentures 2008 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	(8,296)	9,663	(6,639)	3,550
Debentures 2009 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	(1,207)	433	(1,281)	433
Debentures 2010 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	(3,138)	896	(2,515)	896
Debentures 2011 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	(842)	512	(593)	512
Debentures 2012 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	$ (1,063)	$ 314	$ (960)	$ 314