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Investment Income And Gains And Losses (Net Unrealized Gains (Losses), Including Portion Of Other-Than-Temporary Impairments Included In Other Comprehensive Loss, Reported Within Shareholders' Equity) (Details) (USD $) In Millions, unless otherwise specified | Dec. 31, 2011 | Dec. 31, 2010
--- | --- | ---
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Deferred income tax provision (benefit) | $ (86) | $ (208)
Unrealized gains (losses), net | (134) | (392)
Total | (220) | (600)
Fixed-Maturity Investments [Member] |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Gains | 262 | 208
Losses | (459) | (782)
Foreign exchange | (5) | (14)
Net | (202) | (588)
Other Investments [Member] |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Gains | 1 | 10
Losses | (19) | (22)
Net | $ (18) | $ (12)

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