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%
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss) before Taxes	$ (340)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	615	275
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	162	239
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Change in Net Unrealized Holding Gain (Loss) before Taxes	(7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	30	23
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	9	22
Non-redeemable preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	9	22
Twenty Percent Or More [Member] | Six Months Or Greater [Member] | Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	59
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	16
Twenty Percent Or More [Member] | Six Months Or Greater [Member] | Debt Securities [Member] | External Credit Rating, Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	33
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	9
Percentage Of Gross Unrealized Loss	56.00%
Twenty Percent Or More [Member] | Six Months Or Greater [Member] | Debt Securities [Member] | External Credit Rating, Non Investment Grade [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss	26
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	7
Percentage Of Gross Unrealized Loss	44.00%
Twenty Percent Or More [Member] | Twelve months or greater [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	2
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss	$ 6
Twenty Percent Or More [Member] | Twelve months or greater [Member] | Non-redeemable preferred stock [Member] | External Credit Rating, Investment Grade [Member] | Banks, Trust and Insurance, Equities [Member]
Schedule of Available-for-sale Securities [Line Items]
Percentage Of Gross Unrealized Loss	100.00%
Twenty Percent Or More [Member] | Twelve months or greater [Member] | Non-redeemable preferred stock [Member] | Aaa Aa [Member] | Banks, Trust and Insurance, Equities [Member]
Schedule of Available-for-sale Securities [Line Items]
Percentage Of Gross Unrealized Loss	38.00%