Financing (Details 6) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	$ 21,809	$ 13,088
Less: Day-one loss from debenture financings	0	(1,162)
Gain from changes in fair value of hybrid instruments	21,809	11,926
Debentures 2006 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	11,604	2,680
Debentures 2007 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	16,381	798
Debentures 2008 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	13,291	5,433
Debentures 2009 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	2,113	708
Debentures 2010 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	7,177	1,858
Debentures 2011 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	1,748	840
Debentures 2012 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	1,321	771
Debentures 2013 Series [Member]
Debt Conversion [Line Items]
Unrealized Gain Loss On Hybrid Instrument Gross	$ (31,826)	$ 0