Investments (Details 10) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013 contract	Dec. 31, 2012 contract
Fixed income and equity securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	1,554	1,234
Fair value, continuous unrealized loss position for less than 12 months	$ 16,270	$ 3,823
Unrealized losses, continuous unrealized loss position for less than 12 months	(413)	(76)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	319	704
Fair value, continuous unrealized loss position for 12 months or more	1,504	3,471
Unrealized losses, continuous unrealized loss position for 12 months or more	(194)	(488)
Total unrealized losses
Total unrealized losses	(607)	(564)
Fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	1,396	431
Fair value, continuous unrealized loss position for less than 12 months	15,288	3,539
Unrealized losses, continuous unrealized loss position for less than 12 months	(379)	(49)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	318	608
Fair value, continuous unrealized loss position for 12 months or more	1,504	3,402
Unrealized losses, continuous unrealized loss position for 12 months or more	(194)	(481)
Total unrealized losses
Total unrealized losses	(573)	(530)
U.S. government and agencies
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	22	6
Fair value, continuous unrealized loss position for less than 12 months	700	85
Unrealized losses, continuous unrealized loss position for less than 12 months	(7)
Total unrealized losses
Total unrealized losses	(7)
Municipal
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	315	130
Fair value, continuous unrealized loss position for less than 12 months	2,065	1,012
Unrealized losses, continuous unrealized loss position for less than 12 months	(41)	(13)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	38	80
Fair value, continuous unrealized loss position for 12 months or more	208	717
Unrealized losses, continuous unrealized loss position for 12 months or more	(46)	(95)
Total unrealized losses
Total unrealized losses	(87)	(108)
Corporate
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	796	133
Fair value, continuous unrealized loss position for less than 12 months	10,375	1,989
Unrealized losses, continuous unrealized loss position for less than 12 months	(308)	(33)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	54	70
Fair value, continuous unrealized loss position for 12 months or more	550	896
Unrealized losses, continuous unrealized loss position for 12 months or more	(79)	(94)
Total unrealized losses
Total unrealized losses	(387)	(127)
Foreign government
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	36	22
Fair value, continuous unrealized loss position for less than 12 months	262	190
Unrealized losses, continuous unrealized loss position for less than 12 months	(9)	(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	18
Unrealized losses, continuous unrealized loss position for 12 months or more	(2)
Total unrealized losses
Total unrealized losses	(11)	(1)
Asset-backed securities ("ABS")
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	85	12
Fair value, continuous unrealized loss position for less than 12 months	1,715	145
Unrealized losses, continuous unrealized loss position for less than 12 months	(10)	(1)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	43	77
Fair value, continuous unrealized loss position for 12 months or more	429	794
Unrealized losses, continuous unrealized loss position for 12 months or more	(34)	(106)
Total unrealized losses
Total unrealized losses	(44)	(107)
Residential mortgage-backed securities ("RMBS")
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	134	117
Fair value, continuous unrealized loss position for less than 12 months	149	50
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	175	336
Fair value, continuous unrealized loss position for 12 months or more	247	638
Unrealized losses, continuous unrealized loss position for 12 months or more	(26)	(109)
Total unrealized losses
Total unrealized losses	(30)	(110)
Commercial mortgage-backed securities ("CMBS")
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	8	11
Fair value, continuous unrealized loss position for less than 12 months	22	68
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	7	44
Fair value, continuous unrealized loss position for 12 months or more	52	357
Unrealized losses, continuous unrealized loss position for 12 months or more	(7)	(77)
Total unrealized losses
Total unrealized losses	(7)	(77)
Investment grade fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	1,217	387
Fair value, continuous unrealized loss position for less than 12 months	14,019	3,141
Unrealized losses, continuous unrealized loss position for less than 12 months	(340)	(39)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	221	409
Fair value, continuous unrealized loss position for 12 months or more	975	2,172
Unrealized losses, continuous unrealized loss position for 12 months or more	(116)	(217)
Total unrealized losses
Total unrealized losses	(456)	(256)
Below investment grade fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	179	44
Fair value, continuous unrealized loss position for less than 12 months	1,269	398
Unrealized losses, continuous unrealized loss position for less than 12 months	(39)	(10)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	97	199
Fair value, continuous unrealized loss position for 12 months or more	529	1,230
Unrealized losses, continuous unrealized loss position for 12 months or more	(78)	(264)
Total unrealized losses
Total unrealized losses	(117)	(274)
Redeemable preferred stock
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more		1
Equity securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	158	803
Fair value, continuous unrealized loss position for less than 12 months	982	284
Unrealized losses, continuous unrealized loss position for less than 12 months	(34)	(27)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more	1	96
Fair value, continuous unrealized loss position for 12 months or more		69
Unrealized losses, continuous unrealized loss position for 12 months or more		(7)
Total unrealized losses
Total unrealized losses	$ (34)	$ (34)