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Loss And Loss Adjustment Expense Reserves (Schedule Of Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses) (Detail) (USD $) In Millions, unless otherwise specified |  |  | 9 Months Ended
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Sep. 30, 2012 | Dec. 31, 2011 | Sep. 30, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] | Sep. 30, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] Insurance Claim Loss Recoverable [Member] | Sep. 30, 2012 Insurance Loss Recoverable And Changes In Recoveries On Unpaid Losses [Member] Recorded Recoveries [Member]
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |  |
Collections for Cases with Recoveries |  |  | $ (6) | $ (6) |
Accretion of Recoveries |  |  | 36 | 30 | 6
Changes in Discount Rates |  |  | 27 | 8 | 19
Changes in Timing of Collections |  |  |  |  |
Changes in Amount of Collections |  |  | (149) | (149) |
Changes in Assumptions |  |  | 181 | 366 | (185)
Changes in LAE Recoveries |  |  | 14 | 21 | (7)
Gross Reserve beginning balance, Insurance loss recoverable | 3,316 | 3,046 |  |  |
Gross Reserve beginning balance, Recoveries on unpaid losses | 395 | 562 |  |  |
Gross Reserve beginning balance, Total | 3,711 | 3,608 |  |  |
Gross Reserve ending balance, Insurance loss recoverable | 3,316 | 3,046 |  |  |
Gross Reserve ending balance, Recoveries on unpaid losses | 395 | 562 |  |  |
Gross Reserve ending balance, Total | $ 3,711 | $ 3,608 |  |  |

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