Investments (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
U.S. Government and government agencies [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	$ 343	$ 310
Fair Value	349	314
Gross Unrealized, Gains	8	7
Gross Unrealized, Losses	(2)	(3)
States, municipalities and political subdivisions [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	5,979	5,360
Fair Value	6,228	5,372
Gross Unrealized, Gains	281	156
Gross Unrealized, Losses	(32)	(144)
Foreign government [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	128	198
Fair Value	138	208
Gross Unrealized, Gains	10	10
Gross Unrealized, Losses	0	0
Residential Mortgage Backed Securities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	4,274	3,947
Fair Value	4,684	4,310
Gross Unrealized, Gains	428	391
Gross Unrealized, Losses	(18)	(28)
Commercial Mortgage Backed Securities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	2,390	2,535
Fair Value	2,583	2,724
Gross Unrealized, Gains	194	192
Gross Unrealized, Losses	(1)	(3)
Asset-backed Securities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	3,185	2,477
Fair Value	3,219	2,493
Gross Unrealized, Gains	45	35
Gross Unrealized, Losses	(11)	(19)
All other corporate [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	10,988	10,539
Fair Value	11,787	11,035
Gross Unrealized, Gains	820	604
Gross Unrealized, Losses	(21)	(108)
Fixed maturities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	27,287	25,366
Fair Value	28,988	26,456
Gross Unrealized, Gains	1,786	1,395
Gross Unrealized, Losses	(85)	(305)
Common stocks [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	897	721
Fair Value	1,115	914
Gross Unrealized, Gains	233	209
Gross Unrealized, Losses	(15)	(16)
Perpetual preferred stocks [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	341	266
Fair Value	358	265
Gross Unrealized, Gains	21	9
Gross Unrealized, Losses	$ (4)	$ (10)