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Accumulated Other Comprehensive Income (Details Of The Reclassification From AOCI) (Detail) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020
Net gains (losses) on financial instruments at fair value and foreign exchange | $ 51 | $ (63)
Income (loss) before income taxes | (106) | (333)
Net income (loss) | (106) | (333)
Amounts reclassified from AOCI [Member] |  |
Net income (loss) | (15) | 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 | 5 | 3
Income (loss) before income taxes | 5 | 3
Instrument-specific credit risk of liabilities measured at fair value, net [Member] | Amounts reclassified from AOCI [Member] |  |
Net gains (losses) on financial instruments at fair value and foreign exchange | $ (20) | $ (2)

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