Invested Assets (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Change in unrealized appreciation or depreciation of investments carried at fair value [Abstract]
Change in unrealized appreciation of fixed maturities	$ 133	$ 430	$ 116	$ 253
Change in unrealized appreciation of equity securities	(28)	15	74	106
Change in unrealized appreciation of fixed maturities and equity securities	105	445	190	359
Deferred income tax(credit)	37	156	67	126
Total change in unrealized appreciation of fixed maturities and equity securities, Net of tax	$ 68	$ 289	$ 123	$ 233