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Accumulated Other Comprehensive Income (Details Of The Reclassification From AOCI) (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Net gains (losses) on financial instruments at fair value and foreign exchange | $ (24) | $ 84 | $ 63
Income (loss) before income taxes | (661) | (339) | 289
Provision (benefit) for income taxes | 944 | (1) | 109
Net income (loss) | (1,605) | (338) | 180
Amounts reclassified from AOCI [Member] |  |  |
Net income (loss) | (8) | (1) | 1
Unrealized gains (losses) on AFS, net [Member] | Amounts reclassified from AOCI [Member] |  |  |
Net gains (losses) on financial instruments at fair value and foreign exchange | 3 | 7 | 11
Other-than-temporary impairments recognized in accumulated other comprehensive income (loss) | (7) | (4) | (4)
Net investment income | (5) | (6) | (4)
Income (loss) before income taxes | (9) | (3) | 3
Provision (benefit) for income taxes | $ (1) | $ (2) | $ 2

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