Financing (Details 6) (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]
Unrealized Gain On Hybrid Instrument	$ (24,165)	$ 6,668	$ (46,959)	$ 13,120
Less: Day-one loss from debenture financings	0	(315)	0	(1,162)
Gain (loss) from changes in fair value of hybrid instruments	(24,165)	6,353	(46,959)	11,958
Debentures 2006 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	11,069	902	5,754	2,637
Debentures 2007 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	19,420	1,994	13,929	1,005
Debentures 2008 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	16,569	1,914	9,930	5,465
Debentures 2009 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	2,672	477	1,391	912
Debentures 2010 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	9,693	799	7,178	1,695
Debentures 2011 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	635	155	42	666
Debentures 2012 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	1,483	427	523	740
Debentures 2013 Series [Member]
Debt Conversion [Line Items]
Gain (loss) from changes in fair value of hybrid instruments	$ (85,706)	$ 0	$ (85,706)	$ 0