Investments (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
U.S. Government and government agencies [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	$ 360	$ 310
Fair Value	365	314
Gross Unrealized, Gains	7	7
Gross Unrealized, Losses	(2)	(3)
States, municipalities and political subdivisions [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	6,103	5,360
Fair Value	6,370	5,372
Gross Unrealized, Gains	294	156
Gross Unrealized, Losses	(27)	(144)
Foreign government [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	195	198
Fair Value	204	208
Gross Unrealized, Gains	9	10
Gross Unrealized, Losses	0	0
Residential Mortgage Backed Securities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	4,189	3,947
Fair Value	4,589	4,310
Gross Unrealized, Gains	416	391
Gross Unrealized, Losses	(16)	(28)
Commercial Mortgage Backed Securities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	2,328	2,535
Fair Value	2,491	2,724
Gross Unrealized, Gains	163	192
Gross Unrealized, Losses	0	(3)
Asset-backed Securities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	3,601	2,477
Fair Value	3,619	2,493
Gross Unrealized, Gains	37	35
Gross Unrealized, Losses	(19)	(19)
All other corporate [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	11,633	10,539
Fair Value	12,327	11,035
Gross Unrealized, Gains	725	604
Gross Unrealized, Losses	(31)	(108)
Fixed maturities [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	28,409	25,366
Fair Value	29,965	26,456
Gross Unrealized, Gains	1,651	1,395
Gross Unrealized, Losses	(95)	(305)
Common stocks [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	908	721
Fair Value	1,088	914
Gross Unrealized, Gains	216	209
Gross Unrealized, Losses	(36)	(16)
Perpetual preferred stocks [Member]
Available for sale fixed maturities and equity securities
Amortized Cost	371	266
Fair Value	386	265
Gross Unrealized, Gains	19	9
Gross Unrealized, Losses	$ (4)	$ (10)