Investments-Portfolio Monitoring (Details 11) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014 security	Dec. 31, 2013 security
Fixed income and equity securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	335,000,000	686,000,000
Fair value, continuous unrealized loss position for less than 12 months	$ 2,112	$ 5,988
Unrealized losses, continuous unrealized loss position for less than 12 months	(36)	(262)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	222,000,000	165,000,000
Fair value, continuous unrealized loss position for 12 months or more	1,580	1,160
Unrealized losses, continuous unrealized loss position for 12 months or more	(123)	(161)
Total unrealized losses
Total unrealized losses	(159)	(423)
Fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	333,000,000	661,000,000
Fair value, continuous unrealized loss position for less than 12 months	2,104	5,908
Unrealized losses, continuous unrealized loss position for less than 12 months	(36)	(257)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	222,000,000	165,000,000
Fair value, continuous unrealized loss position for 12 months or more	1,580	1,160
Unrealized losses, continuous unrealized loss position for 12 months or more	(123)	(161)
Total unrealized losses
Gross unrealized losses	(159)	(418)
U.S. government and agencies
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	2,000,000	4,000,000
Fair value, continuous unrealized loss position for less than 12 months	21	76
Unrealized losses, continuous unrealized loss position for less than 12 months	0	(2)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	0	0
Fair value, continuous unrealized loss position for 12 months or more	0	0
Unrealized losses, continuous unrealized loss position for 12 months or more	0	0
Total unrealized losses
Total unrealized losses	0	(2)
Municipal
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	12,000,000	63,000,000
Fair value, continuous unrealized loss position for less than 12 months	98	347
Unrealized losses, continuous unrealized loss position for less than 12 months	(2)	(24)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	25,000,000	21,000,000
Fair value, continuous unrealized loss position for 12 months or more	143	99
Unrealized losses, continuous unrealized loss position for 12 months or more	(12)	(38)
Total unrealized losses
Total unrealized losses	(14)	(62)
Corporate
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	278,000,000	530,000,000
Fair value, continuous unrealized loss position for less than 12 months	1,844	5,191
Unrealized losses, continuous unrealized loss position for less than 12 months	(33)	(224)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	119,000,000	48,000,000
Fair value, continuous unrealized loss position for 12 months or more	1,064	467
Unrealized losses, continuous unrealized loss position for 12 months or more	(80)	(71)
Total unrealized losses
Total unrealized losses	(113)	(295)
Foreign government
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	1,000,000	7,000,000
Fair value, continuous unrealized loss position for less than 12 months	7	76
Unrealized losses, continuous unrealized loss position for less than 12 months	0	(4)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	1,000,000	1,000,000
Fair value, continuous unrealized loss position for 12 months or more	14	13
Unrealized losses, continuous unrealized loss position for 12 months or more	(1)	(2)
Total unrealized losses
Total unrealized losses	(1)	(6)
ABS
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	18,000,000	17,000,000
Fair value, continuous unrealized loss position for less than 12 months	129	162
Unrealized losses, continuous unrealized loss position for less than 12 months	(1)	(1)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	26,000,000	42,000,000
Fair value, continuous unrealized loss position for 12 months or more	239	400
Unrealized losses, continuous unrealized loss position for 12 months or more	(22)	(33)
Total unrealized losses
Total unrealized losses	(23)	(34)
RMBS
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	18,000,000	35,000,000
Fair value, continuous unrealized loss position for less than 12 months	2	42
Unrealized losses, continuous unrealized loss position for less than 12 months	0	(2)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	47,000,000	47,000,000
Fair value, continuous unrealized loss position for 12 months or more	77	129
Unrealized losses, continuous unrealized loss position for 12 months or more	(5)	(10)
Total unrealized losses
Total unrealized losses	(5)	(12)
CMBS
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	4,000,000	5,000,000
Fair value, continuous unrealized loss position for less than 12 months	3	14
Unrealized losses, continuous unrealized loss position for less than 12 months	0	0
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	4,000,000	6,000,000
Fair value, continuous unrealized loss position for 12 months or more	43	52
Unrealized losses, continuous unrealized loss position for 12 months or more	(3)	(7)
Total unrealized losses
Total unrealized losses	(3)	(7)
Investment grade fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	143,000,000	526,000,000
Fair value, continuous unrealized loss position for less than 12 months	1,133	5,272
Unrealized losses, continuous unrealized loss position for less than 12 months	(12)	(236)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	172,000,000	110,000,000
Fair value, continuous unrealized loss position for 12 months or more	1,294	834
Unrealized losses, continuous unrealized loss position for 12 months or more	(87)	(112)
Total unrealized losses
Total unrealized losses	(99)	(348)
Below investment grade fixed income securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	190,000,000	135,000,000
Fair value, continuous unrealized loss position for less than 12 months	971	636
Unrealized losses, continuous unrealized loss position for less than 12 months	(24)	(21)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	50,000,000	55,000,000
Fair value, continuous unrealized loss position for 12 months or more	286	326
Unrealized losses, continuous unrealized loss position for 12 months or more	(36)	(49)
Total unrealized losses
Total unrealized losses	(60)	(70)
Equity securities
Less than 12 months
Number of issues, continuous unrealized loss position for less than 12 months	2,000,000	25,000,000
Fair value, continuous unrealized loss position for less than 12 months	8	80
Unrealized losses, continuous unrealized loss position for less than 12 months	0	(5)
12 months or more
Number of issues, continuous unrealized loss position for 12 months or more (in Security)	0	0
Fair value, continuous unrealized loss position for 12 months or more	0	0
Unrealized losses, continuous unrealized loss position for 12 months or more	0	0
Total unrealized losses
Gross unrealized losses on equity securities	$ 0	$ (5)