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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 | Sep. 30, 2011 | Dec. 31, 2010
--- | --- | ---
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Deferred income tax provision (benefit) | $ (76) | $ (208)
Unrealized gains (losses), net | (107) | (392)
Total | (183) | (600)
Fixed-Maturity Investments [Member] |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Gains | 373 | 208
Losses | (536) | (782)
Foreign exchange | 9 | (14)
Net | (154) | (588)
Other Investments [Member] |  |
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items] |  |
Gains | 2 | 10
Losses | (31) | (22)
Net | $ (29) | $ (12)

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