Investments (Details 6) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	$ 29	$ 13	$ 52	$ 33
Realized — impairments	(30)	(1)	(34)	(2)
Fixed maturities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	7	9	10	22
Realized — impairments	(10)	0	(15)	(1)
Change in unrealized	(623)	295	(405)	611
Equity securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	25	4	46	10
Realized — impairments	(23)	(1)	(25)	(1)
Change in unrealized	(21)	30	(15)	43
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	(2)	0	(2)	1
Realized — impairments	0	0	0	0
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	(1)	0	(2)	0
Realized — impairments	3	0	6	0
Change in unrealized	314	(137)	177	(273)
Total Pretax [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	29	13	52	33
Realized — impairments	(30)	(1)	(34)	(2)
Change in unrealized	(330)	188	(243)	381
Tax Effects [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(10)	(4)	(18)	(11)
Realized — impairments	11	0	12	0
Change in unrealized	115	(66)	85	(134)
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)	0	(1)
Realized — impairments	0	0	0	0
Change in unrealized	3	(2)	2	(5)
Marketable Securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	19	8	34	21
Realized — impairments	(19)	(1)	(22)	(2)
Change in unrealized	$ (212)	$ 120	$ (156)	$ 242