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Investment Income And Gains And Losses (Credit Losses Recognized In Earnings Related To OTTI Losses Recognized In Accumulated Other Comprehensive Income (Loss)) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2012 | Jun. 30, 2011 | Jun. 30, 2012 | Jun. 30, 2011
Beginning balance | $ 277 | $ 266 | $ 341 |  | $ 262
Additions for credit loss impairments recognized in the current period on securities previously impaired | 1 | 20 | 3 |  | 27
Reductions for credit loss impairments previously recognized on securities sold during the period | (9) | (3) | (16) |  | (6)
Reductions for credit loss impairments previously recognized on securities impaired to fair value during the period(1) |  |  | (59) | [1] |
Ending balance | $ 269 | $ 283 | $ 269 |  | $ 283
[1] | Represents circumstances where the Company determined in the current period that it intends to sell the security or it is more likely than not that it will be required to sell the security before recovery of the security's amortized cost.

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- Definition Additions For Credit Loss Impairments Recognized In The Current Period On Securities Previously Impaired + References No definition available. + Details
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- Definition Marketable securities credit losses recognized in earnings other than temporary impairments amount. + References No definition available. + Details
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- Definition Reductions for credit loss impairments previously recognized on securities impaired to fair value during the period. + References No definition available. + Details
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- Definition Reductions For Credit Loss Impairments Previously Recognized On Securities Sold During The Period + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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