Investment Income and Gains and Losses - Realized Investment Gains and Losses (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Realized Gains (Losses) on Investments [Line Items]
Realized investment gains (losses) before income taxes	$ 213		$ 44		$ 62
Less income taxes (benefits)	72		13		21
Net realized investment gains (losses)	141		31		41
Impairments Table Details [Abstract]
Credit-related	(8)	[1]	(20)	[1]	(28)	[1]
Other	(21)		(2)		(25)
Total	(29)		(22)		(53)
Credit losses on fixed maturities for which a portion of the impairment was recognized in other comprehensive income	0		0		0
Pre-tax gains (losses) on hybrid securities	3		5		(7)
Realized Investment Results Not Reflected In Revenues Table Details [Abstract]
Separate accounts	417		206		210
Investment gains required to adjust future policy benefits for the run-off settlement annuity business	9		21		8
Sales Information For Available For Sale Fixed Maturities Equity Securities [Abstract]
Proceeds from sales	1,775		591		876
Gross gains on sales	102		37		53
Gross losses on sales	4		2		7
Fixed Maturities [Member]
Realized Gains (Losses) on Investments [Line Items]
Realized investment gains (losses) before income taxes	113		48		50
Equity securities [Member]
Realized Gains (Losses) on Investments [Line Items]
Realized investment gains (losses) before income taxes	8		4		(1)
Commercial Mortgage Loans [Member]
Realized Gains (Losses) on Investments [Line Items]
Realized investment gains (losses) before income taxes	(3)		(9)		(16)
Real Estate [Member]
Realized Gains (Losses) on Investments [Line Items]
Realized investment gains (losses) before income taxes	0		(1)		(6)
Other Investments Including Derivatives [Member]
Realized Gains (Losses) on Investments [Line Items]
Realized investment gains (losses) before income taxes	$ 95		$ 2		$ 35

[1] There were no credit losses on fixed maturities for which a portion of the impairment was recognized in other comprehensive income.