Investments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments [Abstract]
Number of non-income producing fixed maturity securities		9
Fair value of non income fixed maturity security		$ 1
Number of investments that exceed ten percent of stockholders' equity
Limited partnership investments	2,720	2,462
Undistributed earnings of limited partnership investments	969	768
Percentage of limited partnerships reported on a current basis	67.00%
Percentage of limited partnerships reported on a one month lag	16.00%
Number of active limited partnership investments held	87	79
Percentage of limited partnerships employing hedge fund strategies focused on fixed income and equity investments	74.00%	80.00%
Percentage of equity related limited partnership hedge fund strategies	51.00%
Percentage of multistrategy approach limited partnership hedge fund strategies	28.00%
Percentage of distressed investments limited partnership hedge fund strategies	17.00%
Percentage of fixed income limited partnership hedge fund strategies	4.00%
Limited partnerships invested in private debt and equity	22.00%	16.00%
Carrying value of ten largest limited partnerships	1,471	1,309
Carrying value of limited partnerships as percentage of aggregate partnership equity	4.00%	4.00%
Income As Percentage Of Change In Partnership Equity For All Limited Partnerships	4.00%	3.00%	4.00%
Commercial mortgage loans past due or in non-accrual status
Valuation allowances recorded on commercial mortgage loans
Future capital call commitments for limited partnership investments	381
Commitments to purchase or fund privately placed debt securities	151
Commitments to sell various privately placed debt securities	145
Carrying value of securities deposited under requirements of regulatory authorities	3,300	3,600
Cash and securities deposited as collateral for letters of credit	353	4
Carrying value of assets deposited to secure reinsurance and third party obligations	$ 294	$ 277