Investments - Realized Investment Gains and Losses (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
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)	$ 27	$ 11	$ 192	$ 20
Less income taxes (benefits)	10	4	65	4
Realized investment gains (losses) from continuing operations, net of taxes and noncontrolling interest	17	7	127	16
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)	16	8	105	23
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)	0	1	4	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)	0	1	(4)	(9)
Real estate [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)	0	0	0	(1)
Other Investments Including Derivatives [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)	$ 11	$ 1	$ 87	$ 2