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Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses) (Details) (Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member], USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |
Gross Reserve as of beginning balance, Total | $ 3,427 | $ 3,276 |
Accounting Transition Adjustment |  | (809) | [1]
Collections for Cases with Recoveries | (101) | (81) |
Accretion of Recoveries | 73 | 51 |
Changes in Discount Rates | 117 | (11) |
Changes in Timing of Collections |  | 33 |
Changes in Amount of Collections | (227) | (64) |
Changes in Assumptions | 307 | 1,049 |
Changes in LAE Recoveries | 12 | (17) |
Gross Reserve as of ending balance, Total | 3,608 | 3,427 |
Insurance Loss Recoverable [Member] |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |
Gross Insurance Loss Recoverable, beginning balance | 2,531 | 2,445 |
Accounting Transition Adjustment |  | (594) | [1]
Collections for Cases with Recoveries | (101) | (81) |
Accretion of Recoveries | 57 | 36 |
Changes in Discount Rates | 49 | (10) |
Changes in Timing of Collections |  | 33 |
Changes in Amount of Collections | (227) | (56) |
Changes in Assumptions | 723 | 790 |
Changes in LAE Recoveries | 14 | (32) |
Gross Insurance Loss Recoverable, ending balance | 3,046 | 2,531 |
Recoveries On Unpaid Losses [Member] |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |
Gross Reserve as of beginning balance, Recoveries on Unpaid Losses | 896 | 831 |
Accounting Transition Adjustment |  | (215) | [1]
Accretion of Recoveries | 16 | 15 |
Changes in Discount Rates | 68 | (1) |
Changes in Amount of Collections |  | (8) |
Changes in Assumptions | (416) | 259 |
Changes in LAE Recoveries | (2) | 15 |
Gross Reserve as of ending balance, Recoveries on Unpaid Losses | $ 562 | $ 896 |
[1] | Reflects the adoption of the accounting principles for the consolidation of variable interest entities.

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