Long-Term Debt (Details 1) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Extinguishment of Debt [Line Items]
Extinguishment of Debt, Amount	$ 515
Securitization Bonds [Member]
Extinguishment of Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.42%
Extinguishment of Debt, Amount	88
Tax Exempt Revenue Bonds [Member]
Extinguishment of Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.30%
Extinguishment of Debt, Amount	51
Long-term Debt [Member]
Extinguishment of Debt [Line Items]
Extinguishment of Debt, Amount	3
Senior Notes [Member]
Extinguishment of Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.26%
Extinguishment of Debt, Amount	60
Senior Notes 1 [Member]
Extinguishment of Debt [Line Items]
Extinguishment of Debt, Amount	300
Long Term Debt, Other [Member]
Extinguishment of Debt [Line Items]
Extinguishment of Debt, Amount	$ 13