Investments (Details 10) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013 security	Dec. 31, 2012 security
Fixed income and equity securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	686	160
Fair value, continuous unrealized loss position for less than 12 months	$ 5,988	$ 1,513
Unrealized losses, continuous unrealized loss position for less than 12 months	(262)	(36)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	165	401
Fair value, continuous unrealized loss position for 12 months or more	1,160	2,787
Unrealized losses, continuous unrealized loss position for 12 months or more	(161)	(391)
Total unrealized losses
Total unrealized losses	(423)	(427)
Fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	661	157
Fair value, continuous unrealized loss position for less than 12 months	5,908	1,456
Unrealized losses, continuous unrealized loss position for less than 12 months	(257)	(35)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	165	400
Fair value, continuous unrealized loss position for 12 months or more	1,160	2,787
Unrealized losses, continuous unrealized loss position for 12 months or more	(161)	(391)
Total unrealized losses
Gross unrealized losses	(418)	(426)
U.S. government and agencies
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	4	1
Fair value, continuous unrealized loss position for less than 12 months	76	15
Unrealized losses, continuous unrealized loss position for less than 12 months	(2)
Total unrealized losses
Total unrealized losses	(2)
Municipal
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	63	11
Fair value, continuous unrealized loss position for less than 12 months	347	101
Unrealized losses, continuous unrealized loss position for less than 12 months	(24)	(7)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	21	50
Fair value, continuous unrealized loss position for 12 months or more	99	395
Unrealized losses, continuous unrealized loss position for 12 months or more	(38)	(54)
Total unrealized losses
Total unrealized losses	(62)	(61)
Corporate
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	530	79
Fair value, continuous unrealized loss position for less than 12 months	5,191	1,086
Unrealized losses, continuous unrealized loss position for less than 12 months	(224)	(27)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	48	66
Fair value, continuous unrealized loss position for 12 months or more	467	829
Unrealized losses, continuous unrealized loss position for 12 months or more	(71)	(86)
Total unrealized losses
Total unrealized losses	(295)	(113)
Foreign government
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	7	2
Fair value, continuous unrealized loss position for less than 12 months	76	121
Unrealized losses, continuous unrealized loss position for less than 12 months	(4)	(1)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	1
Fair value, continuous unrealized loss position for 12 months or more	13
Unrealized losses, continuous unrealized loss position for 12 months or more	(2)
Total unrealized losses
Total unrealized losses	(6)	(1)
ABS
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	17	5
Fair value, continuous unrealized loss position for less than 12 months	162	38
Unrealized losses, continuous unrealized loss position for less than 12 months	(1)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	42	76
Fair value, continuous unrealized loss position for 12 months or more	400	763
Unrealized losses, continuous unrealized loss position for 12 months or more	(33)	(105)
Total unrealized losses
Total unrealized losses	(34)	(105)
RMBS
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	35	49
Fair value, continuous unrealized loss position for less than 12 months	42	30
Unrealized losses, continuous unrealized loss position for less than 12 months	(2)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	47	164
Fair value, continuous unrealized loss position for 12 months or more	129	442
Unrealized losses, continuous unrealized loss position for 12 months or more	(10)	(69)
Total unrealized losses
Total unrealized losses	(12)	(69)
CMBS
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	5	10
Fair value, continuous unrealized loss position for less than 12 months	14	65
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	6	43
Fair value, continuous unrealized loss position for 12 months or more	52	358
Unrealized losses, continuous unrealized loss position for 12 months or more	(7)	(77)
Total unrealized losses
Total unrealized losses	(7)	(77)
Redeemable preferred stock
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more		1
Investment grade fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	526	132
Fair value, continuous unrealized loss position for less than 12 months	5,272	1,244
Unrealized losses, continuous unrealized loss position for less than 12 months	(236)	(29)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	110	262
Fair value, continuous unrealized loss position for 12 months or more	834	1,919
Unrealized losses, continuous unrealized loss position for 12 months or more	(112)	(195)
Total unrealized losses
Total unrealized losses	(348)	(224)
Below investment grade fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	135	25
Fair value, continuous unrealized loss position for less than 12 months	636	212
Unrealized losses, continuous unrealized loss position for less than 12 months	(21)	(6)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	55	138
Fair value, continuous unrealized loss position for 12 months or more	326	868
Unrealized losses, continuous unrealized loss position for 12 months or more	(49)	(196)
Total unrealized losses
Total unrealized losses	(70)	(202)
Equity securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	25	3
Fair value, continuous unrealized loss position for less than 12 months	80	57
Unrealized losses, continuous unrealized loss position for less than 12 months	(5)	(1)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more		1
Total unrealized losses
Gross unrealized losses on equity securities	$ (5)	$ (1)