Investments (Roll-Forward Of Pre-Tax Credit Losses Related To Fixed Maturities For Which A Portion Of OTTI Was Recognized In OCI) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Investments [Abstract]
Balance of credit losses related to securities still held- beginning of period	$ 74	$ 137
Additions where no OTTI was previously recorded	1
Additions where an OTTI was previously recorded	5	1
Reductions for securities sold during the period	(25)	(42)
Balance of credit losses related to securities still held- end of period	$ 55	$ 96