Investments (Details Textuals 9) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Equity securities available-for-sale with gross unrealized loss of equal to or greater than stated percentage	20.00%	20.00%
% A Rated or Better	20.00%
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	199	299
Non-redeemable preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	157	202
20% or more [Member] | Non-redeemable preferred stock [Member] | Financial Services Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
% Financial Service Industry securities with losses of 20% or more to total equity securities with losses of 20% or more	90.00%
20% or more [Member] | Twelve months or greater [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	124	96
20% or more [Member] | Twelve months or greater [Member] | Non-redeemable preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	124
20% or more [Member] | Twelve months or greater [Member] | Non-redeemable preferred stock [Member] | Investment Grade [Member] | Financial Services Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	115
% A Rated or Better	72.00%
20% or more [Member] | All equity securities with a gross unrealized loss of 20% or more [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	166
20% or more [Member] | All equity securities with a gross unrealized loss of 20% or more [Member] | Non-redeemable preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	145
20% or more [Member] | All equity securities with a gross unrealized loss of 20% or more [Member] | Non-redeemable preferred stock [Member] | Financial Services Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	0
20% or more [Member] | All equity securities with a gross unrealized loss of 20% or more [Member] | Non-redeemable preferred stock [Member] | Investment Grade [Member] | Financial Services Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	123
% A Rated or Better	74.00%