Financing (Details 8) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Unrealized Gain Loss On Hybrid Instrument Gross	$ 6,668	$ 17,631	$ 13,120	$ 4,203
Day-one loss from derivative financings	(315)	0	(1,162)	0
Change in fair value of hybrid financial instruments	6,353	17,631	11,958	4,203
Debentures 2007 Series [Member]
Change in fair value of hybrid financial instruments	1,994	13,120	1,005	3,088
Debentures 2008 Series [Member]
Change in fair value of hybrid financial instruments	1,914	4,511	5,465	1,115
Debentures 2006 Series [Member]
Change in fair value of hybrid financial instruments	902	0	2,637	0
Debentures 2009 Series [Member]
Change in fair value of hybrid financial instruments	477	0	912	0
Debentures 2010 Series [Member]
Change in fair value of hybrid financial instruments	799	0	1,695	0
Debentures 2011 Series [Member]
Change in fair value of hybrid financial instruments	155	0	666	0
Debentures 2012 Series [Member]
Change in fair value of hybrid financial instruments	$ 427	$ 0	$ 740	$ 0