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Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses) (Details) (USD $) In Millions, unless otherwise specified |  |  | 3 Months Ended
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Mar. 31, 2012 Non Variable Interest Entities [Member] | Dec. 31, 2011 Non Variable Interest Entities [Member] | Mar. 31, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] | Mar. 31, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] Insurance Loss Recoverable [Member] | Mar. 31, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] Recoveries On Unpaid Losses [Member]
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |
Gross Reserve as of December 31, 2011, Insurance loss recoverable | $ 3,137 | $ 3,046 |  | $ 3,046 |
Gross Reserve as of December 31, 2011, Recoveries on unpaid losses |  |  |  |  | 562
Gross Reserve as of December 31, 2011, Total |  |  | 3,608 |  |
Collections for Cases with Recoveries |  |  | (2) | (2) |
Accretion of Recoveries |  |  | 11 | 9 | 2
Changes in Discount Rates |  |  | (27) | (12) | (15)
Changes in Timing of Collections |  |  |  |  |
Changes in Amount of Collections |  |  | (63) | (63) |
Changes in Assumptions |  |  | 122 | 152 | (30)
Changes in LAE Recoveries |  |  | 6 | 7 | (1)
Gross Reserve as of March 31, 2012, Insurance loss recoverable | 3,137 | 3,046 |  | 3,137 |
Gross Reserve as of March 31, 2012, Recoveries on unpaid losses |  |  |  |  | 518
Gross Reserve as of March 31, 2012, Total |  |  | $ 3,655 |  |

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