Investment Income and Gains and Losses (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Total realized investment gains (losses)	$ 44		$ 62		$ 75
Less income taxes (benefits)	13		21		25
Realized investment gains (losses) from continuing operations, net of taxes and noncontrolling interest	31		41		50
Impairments Table Details [Abstract]
Credit-related	(20)	[1]	(28)	[1]	(38)	[1]
Other	(2)		(25)		(1)
Total	(22)		(53)		(39)
Realized Investment Results Not Reflected In Revenues Table Details [Abstract]
Separate accounts	206		210		191
Investment gains required to adjust future policy benefits for the run-off settlement annuity business	21		8		18
Sales Information For Available For Sale Fixed Maturies Equity Securities [Abstract]
Proceeds from sales	591		876		826
Gross gains on sales	37		53		46
Gross losses on sales	(2)		(7)		(3)
Investment Income And Gains And Losses Text Details [Abstract]
Net Investment Income Not Reflected In Revenues Separate Accounts	181		207		163
Realized Investment Gains Losses On Hybrid Securities	5		(7)		7
Fixed Maturities [Member]
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Total realized investment gains (losses)	48		50		87
Equity securities [Member]
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Total realized investment gains (losses)	4		(1)		5
Commercial Mortgage Loans [Member]
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Total realized investment gains (losses)	(9)		(16)		(23)
Real estate and mortgage loans, including pooled separate accounts [Member]
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Total realized investment gains (losses)	(1)		(6)		3
Other Long Term Investments [Member]
Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]
Total realized investment gains (losses)	$ 2		$ 35		$ 3

[1] Credit-related losses include other-than-temporary declines in fair value of fixed maturities and equity securities and changes in valuation reserves and asset write-downs related to commercial mortgage loans and investments in real estate entities. There were no credit losses on fixed maturities for which a portion of the impairment was recognized in other comprehensive income.