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Investments (Net Unrealized Gains (Losses), Including Portion Of Other-Than-Temporary Impairments Included In Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2012 | Dec. 31, 2011
--- | --- | ---
Schedule of Investments [Line Items] |  |
Gross unrealized gains | $ 251 | $ 263
Gross unrealized losses | (152) | (478)
Foreign exchange | 24 | (5)
Net | 123 | (220)
Deferred income tax provision (benefit) | 31 | (86)
Unrealized gains (losses), net | $ 92 | $ (134)

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- Definition The gross unrealized losses, including the portion of other-than-temporary impairments included In accumulated other comprehensive income loss for available-for-sale securities as of the balance sheet date. + References No definition available. + Details
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