Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	$ 13		$ 42		$ 33		$ 99
Realized — impairments	(1)		(1)		(2)		(1)
Fixed maturities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	9		8		22		27
Realized — impairments	0		0		(1)		0
Change in unrealized	295		(725)		611		(740)
Equity securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	4		33		10		71
Realized — impairments	(1)		0		(1)		0
Change in unrealized	30		(13)		43		54
Mortgage Loans and Other Investments [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	0		1		1		2
Realized — impairments	0		(1)		0		(1)
Change in unrealized	0		0		0		0
Other [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	0	[1]	0	[1]	0	[1]	(1)	[1]
Realized — impairments	0	[1]	0	[1]	0	[1]	0	[1]
Change in unrealized	(137)	[1]	319	[1]	(273)	[1]	333	[1]
Tax Effects [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(4)		(15)		(11)		(35)
Realized — impairments	0		0		0		0
Change in unrealized	(66)		147		(134)		124
Noncontrolling Interests [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(1)		0		(1)		(1)
Realized — impairments	0		0		0		0
Change in unrealized	(2)		7		(5)		6
Marketable Securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	8		27		21		63
Realized — impairments	(1)		(1)		(2)		(1)
Change in unrealized	$ 120		$ (265)		$ 242		$ (223)

[1] Primarily adjustments to deferred policy acquisition costs and reserves related to annuities and long-term care business.