Investments (Fixed Maturities Proceeds)(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Fixed maturity and equity security impairments
Net writedowns for other-than-temporary impairment losses on fixed maturities recognized in earnings	$ (95)	[1]	$ (116)	[1]	$ (300)	[1]	$ (373)	[1]
Writedowns for impairments on equity securities	(24)		(42)		(114)		(101)
Equity Securities [Member]
Available For Sale
Gross investment gains from sales	125		94		339		403
Available-for-sale Securities, Gross Realized Losses	(61)		(106)		(222)		(176)
Equity securities, available for sale
Proceeds From Sale Of Available For Sale Securities Equity Including Not Settled	1,101		1,168		3,251		2,854
Fixed Maturities, Available For Sale [Member]
Available For Sale
Proceeds from sales	2,682		8,333		12,140		19,262
Proceeds from maturities/repayments	5,509		3,804		15,794		13,062
Gross investment gains from sales	129		188		397		630
Available-for-sale Securities, Gross Realized Losses	(87)		(74)		(245)		(255)
Fixed Maturities, Held To Maturity [Member]
Fixed maturities, held to maturity
Proceeds from maturities/repayments	132		68		379		338
Gross investment gains from prepayments	$ 0		$ 0		$ 0		$ 0

[1] Excludes the portion of other-than-temporary impairments recorded in “Other comprehensive income (loss),” representing any difference between the fair value of the impaired debt security and the net present value of its projected future cash flows at the time of impairment.