Financial Derivatives (Credit Ratings of Credit Default Swaps) (Details) (Underlying Other Beneficiary [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Notional Amount of Credit Risk Derivatives	$ 95	$ 110
External Credit Rating, Investment Grade [Member]
Notional Amount of Credit Risk Derivatives	95	95
External Credit Rating, Non Investment Grade [Member]
Notional Amount of Credit Risk Derivatives	$ 0	$ 15