Investments (Evaluation of Available-For-Sale Securities for OTTI and Evaluating Temporarily Impaired AFS Securities - Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
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%
Fixed maturity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Change in Gross Unrealized Temporary Loss	$ 2,500
Gross Unrealized Temporary Loss	4,200	1,700
Gross Unrealized Temporary Loss	978	1,455
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Change in Gross Unrealized Temporary Loss	(26)
Gross Unrealized Temporary Loss	133	159
Gross Unrealized Temporary Loss	61	141
Non-redeemable preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	60	140
20% or more [Member] | Six months or greater [Member] | Fixed maturity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	282
Number of Securities	95
20% or more [Member] | Six months or greater [Member] | Fixed maturity securities [Member] | Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	129
Number of Securities	48
Percentage of gross unrealized loss	46.00%
20% or more [Member] | Six months or greater [Member] | Fixed maturity securities [Member] | Below Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Temporary Loss	153
Number of Securities	47
Percentage of gross unrealized loss	54.00%
20% or more [Member] | Twelve months or greater [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of Securities	13
Gross Unrealized Temporary Loss	$ 46
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]
Percentage of gross unrealized loss	100.00%
20% or more [Member] | Twelve months or greater [Member] | Non-redeemable preferred stock [Member] | Aaa/Aa/A [Member] | Financial Services Industry [Member]
Schedule of Available-for-sale Securities [Line Items]
Percentage of gross unrealized loss	63.00%