Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	$ 24	$ 61	$ 57	$ 160
Realized — impairments	(11)	(5)	(13)	(6)
Fixed maturities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	10	6	32	33
Realized — impairments	(9)	0	(10)	0
Change in unrealized	(145)	(57)	466	(797)
Equity securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	16	54	26	125
Realized — impairments	(5)	(5)	(6)	(5)
Change in unrealized	(40)	(28)	3	26
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)	0	0	2
Realized — impairments	0	0	0	(1)
Change in unrealized	0	0	0	0
Other, Including DPAC and Reserves on Annuity and Long-term Care [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(1)	1	(1)	0
Realized — impairments	3	0	3	0
Change in unrealized	60	37	(213)	370
Tax Effects [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(10)	(22)	(21)	(57)
Realized — impairments	5	2	5	2
Change in unrealized	44	16	(90)	140
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)	(1)	(2)
Realized — impairments	0	0	0	0
Change in unrealized	2	0	(3)	6
Marketable Securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	14	38	35	101
Realized — impairments	(6)	(3)	(8)	(4)
Change in unrealized	$ (79)	$ (32)	$ 163	$ (255)