Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	$ 20		$ 57
Realized — impairments	(1)		0
Fixed maturities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	13		19
Realized — impairments	(1)		0
Change in unrealized	316		(15)
Equity securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	6		38
Realized — impairments	0		0
Change in unrealized	13		67
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	1		1
Realized — impairments	0		0
Change in unrealized	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]	(1)	[1]
Realized — impairments	0	[1]	0	[1]
Change in unrealized	(136)	[1]	14	[1]
Tax Effects [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(7)		(20)
Realized — impairments	0		0
Change in unrealized	(68)		(23)
Noncontrolling Interests [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	0		(1)
Realized — impairments	0		0
Change in unrealized	(3)		(1)
Marketable Securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	13		36
Realized — impairments	(1)		0
Change in unrealized	$ 122		$ 42

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