Fair Value (Narrative) (Details) (USD $) In Millions, unless otherwise specified					9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Net Embedded Derivatives [Member]	Dec. 31, 2012 Net Embedded Derivatives [Member]	Sep. 30, 2013 Private Equity And Debt Funds [Member] Minimum [Member]	Sep. 30, 2013 Private Equity And Debt Funds [Member] Maximum [Member]	Sep. 30, 2013 Real Estate Funds [Member] Minimum [Member]	Sep. 30, 2013 Real Estate Funds [Member] Maximum [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Liquidation period					2 years	10 years	1 year	10 years
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Equity Securities	$ 3,241	$ 2,891	$ (136)	$ (88)