Investments (Details 14) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Changes in fixed maturity securities with noncredit OTTI losses in accumulated other comprehensive income (loss)
Balance, beginning of period	$ (724)	$ (601)
Noncredit OTTI losses recognized	(2)	31
Securities sold with a previous noncredit OTTI loss	50	125
Subsequent increases in estimated fair value	8	(279)
Balance, end of period	$ (668)	$ (724)

Pre tax reclassification adjustment for gains or losses realized upon the sale of securities.

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+ Details