Invested Assets and Related Income (Details 6) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in unrealized appreciation or depreciation of investments carried at fair value [Abstract]
Change in unrealized appreciation of fixed maturities	$ 964	$ 70	$ 1,524
Change in unrealized appreciation of equity securities	(17)	47	302
Change in unrealized appreciation of fixed maturities and equity securities	947	117	1,826
Deferred income tax	331	41	639
Total change in unrealized appreciation of fixed maturities and equity securities, Net of tax	$ 616	$ 76	$ 1,187