Investments (Details 20) (USD $) In Millions, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	$ 115	$ 241
% A Rated or Better	20.00%
Less than six months [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	0
% of All Equity Securities	0.00%
Less than six months [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | All Industries [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	0
% of All Non-Redeemable Preferred Stock	0.00%
Less than six months [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | Financial Services Industry [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	0
% of All Industries	0.00%
% A Rated or Better	0.00%
Less than six months [Member] | 20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	4
Six months or greater but less than twelve months [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	0
% of All Equity Securities	0.00%
Six months or greater but less than twelve months [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | All Industries [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	0
% of All Non-Redeemable Preferred Stock	0.00%
Six months or greater but less than twelve months [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | Financial Services Industry [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	0
% of All Industries	0.00%
% A Rated or Better	0.00%
Six months or greater but less than twelve months [Member] | 20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	0
Twelve months or greater [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69
% of All Equity Securities	100.00%
Twelve months or greater [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | All Industries [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69
% of All Non-Redeemable Preferred Stock	100.00%
Twelve months or greater [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | Financial Services Industry [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69
% of All Industries	100.00%
% A Rated or Better	72.00%
Twelve months or greater [Member] | 20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69	116
All equity securities with a gross unrealized loss of 20% or more [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69
% of All Equity Securities	95.00%
All equity securities with a gross unrealized loss of 20% or more [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | All Industries [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69
% of All Non-Redeemable Preferred Stock	100.00%
All equity securities with a gross unrealized loss of 20% or more [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | Financial Services Industry [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69
All equity securities with a gross unrealized loss of 20% or more [Member] | Non-redeemable preferred stock [Member] | 20% or more [Member] | Financial Services Industry [Member] | Investment Grade [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	69
% of All Industries	100.00%
% A Rated or Better	72.00%
20% or more [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	73
Non-redeemable preferred stock [Member]
Equity securities available-for-sale with a gross unrealized loss of 20%or more
Gross Unrealized Loss	$ (104)	$ (229)